which as large quantities as possible of putrescible matter were placed in contact with the smallest possible quantities of oxygen.

The matters which I made use of, viz. urine, blood, soup, yeast, and milk, as well as water and raw meat, and grains of rice, beans, peas, pieces of coagulated albumen, &c., taken in a fresh state, were infected by bacteria taken from similar matters in a state of full putrefaction. The flasks were then sealed and exposed to a temperature of 38-40 degrees; putrefaction was immediately established, to be definitely arrested, however, in all the flasks after a longer or shorter period, often very short, but always sensibly proportional to the quantity of oxygen which was supposed to be present. I have had in my possession for nearly two years a considerable number of these flasks whose contents have lost little or nothing of their primitive freshness.

The details of these experiments are related in a memoir which has been published in the Annals of the Academy of Sciences, Amsterdam,' vol. xii., 1878, and in the sixth part for the year 1878 of the Journal of Practical Chemistry,' as well as the arguments which led me to attribute the cessation of the putrefaction solely to the death of the bacteria caused by the absence of free oxygen.

I will ask permission to cite here one of these arguments, because it relates especially to a subject which has often occupied this Academy.

When the flasks containing the putrescible matters terminate in tubes provided with cotton-wool, or are re-curved many times upon themselves, and whose tapered points are hermetically sealed, we are able at any given moment by breaking the point to expose the contents anew to the contact of the air, deprived of germs. If to establish this contact we wait for the moment when the contents have arrived at a state of complete inertia, we observe that the air no longer produces the least phenomenon of putrefaction or appreciable alteration. This proves in my opinion not only that the bacteria as well as their germs are really dead, but also that the organic matters are not susceptible of spontaneously producing others. These experiments are then, as it seems to me, very strong arguments against archebiosis, and so much the more that the organic matters are not subjected here to any other manipulation than the seclusion during several days or weeks of the air-a manipulation which produces no alteration either in colour, structure, or solubility, and which seems to preserve them as much as possible in their natural state.

This is why I have applied this method to the well-known experiments of M. Bastian with urine neutralized by potash; my procedure was the same as his, with this difference, that no measures were taken to sterilize the matter operated on; on the contrary, it was mixed with a drop of urine in full putrefaction. A certain number of flasks of about 500 cubic centimetres capacity were filled as completely as possible with this prepared urine, then sealed and exposed to a temperature of 40°. The urine got thick, but became perfectly limpid again at the end of some days; it then remained in this state without change of colour and without presenting any other sign of

alteration. Other flasks arranged in the same manner, but whose tapered necks terminated in orifices of different size, allowed me to observe not only that the putrefaction was clearly established, but that its intensity was sensibly proportional to the quantity of air which could enter. It was easy in this way to set up putrefaction at all degrees, from zero to the maximum, in different portions of the same matter eminently putrescible and infected, whose conditions of existence presented no other difference than that of the greater or less free access of air.

Urine neutralized by potash must be considered a matter eminently fit for the life of micro-organisms, and extremely difficult to sterilize by the ordinary methods; but from the moment when the organisms which it contains no longer find oxygen, they lose completely the faculty of supporting the bacteria, and with greater reason the faculty of producing others.

The seclusion of oxygen offers a simple means, generally applicable and efficacious, for sterilizing organic matters, and furnishes the most conclusive proofs against spontaneous generation.

M. Pasteur, after the above communication had been read, made the following remarks:-It is seventeen years since I published the first facts relative to life without air or anaerobiosis; since this time I have occupied myself with the cause of error which the author refers to in the preceding note, and notwithstanding the very great precision, as I think, of my first experiments, I have always endeavoured since then to make this precision more perfect. Very recently, on the occasion of the remarks which I published in conjunction with Messrs. Joubert and Chamberland, we carried still further the investigation of the means proper for eliminating in a complete manner the air from our flasks. With this end we combined the action of the vacuum of the mercury air-pump with the properties of white indigo, a substance so well known for its effect in the absorption of oxygen since the work of M. Dumas on the subject.

If the author of the preceding note will go further in his observation, if he will remark, as he does not seem to have done, that putrefaction is often arrested not by the death of the microscopic organisms, but because they have passed to the state of germs, I do not doubt but that he will be led, as was the case with Dr. Brefeld in regard to the development of alcoholic yeast, to retract his assertions, and to recognize that the existence of anaerobic beings rests on irrefutable proofs.

In the second part of his note M. Gunning combats the conclusion of Dr. Bastian on spontaneous generation, and I am glad of the confirmation which he brings to the arguments which I have already used against the latter gentleman.

Haliphysema Tumanowiczii, not a Sponge.-In the July number of the Annals of Nat. Hist.,' Mr. W. Saville Kent records the results of an examination he has made at Jersey of some specimens of this organism found on the fronds and root-stalk of Maugeria sanguinea, in regard to which so much controversy has arisen.

Prior to the discovery of the living specimens, Mr. Kent had

made an examination of a dried one, which, though not definitely solving the question, had tended to confirm an affinity to the sponges, within the interior being found one or more minute fragments which bore a strong resemblance, under a magnification of 800 diameters, to a pavement-like arrangement of the essential collar-bearing spongozoa in a desiccated state.

When the living specimens were obtained they were in the first place transferred to a shallow zoophyte trough, and cursorily reconnoitred with a power of from 100 to 200 diameters only. This preliminary inspection yielded no positive results, the spicule-bristling capitulum in each instance maintaining the mute stolidity of the sphinx itself, and altogether refusing to yield up its secret. In one or two instances, however, there was the ghost of an appearance of syncitium-like sarcode embracing the base of some of the larger spicules. At the same time (and this must be accepted as a somewhat significant fact) not the slightest inward or outward current from the terminal orifice or any other region could be detected on adding a solution of carmine to the water, which may be almost immediately observed when experimenting in a similar manner on a living sponge. Proceeding now to a more intimate acquaintance with the organism, a lucky cut with a dissecting knife had the gratifying result of dividing a specimen evenly and longitudinally from one end to the other; and this, submitted to no higher a magnifying power than the one previously employed, at once solved the riddle. Cord-like prolongations of moving granular sarcode were seen at the severed edges extending from one to another of the projecting surfaces of the quartz granules or spicular fragments of which the skeletal framework was composed. Here and there these cord-like prolongations were, as it were, knotted into fusiform or globular dilatations, and these, by the contraction in opposite directions of the thinner portions, were now and then drawn slowly across from one end to the other of the same. The sarcode substance of the more interior portion corresponded closely with that of the knotted dilatations, except that in this more densely aggregated condition it presented a darker amber-like aspect. In a little while still finer thread-like extensions of this sarcode were thrust out from the denser mass, some as slender, attenuate, simple filaments, while others assumed a more or less branching form. Here and there the ramifications of these latter came into contact and anastomosed with one another, while in all was maintained a circulation of the granular contents identical in all ways with what obtains among the typical Foraminifera, such as Miliola and Rotalia. A still more rigid examination with the aid of a magnifying power of from 800 to as much as 2000 diameters failed to reveal the existence of any structures corresponding with the collar-bearing flagellate zooids of ordinary sponges, or, indeed, of any separate cellular elements whatever. Occasionally the globular or fusiform sarcode dilatations already mentioned exhibited, under this increased magnifying power, the presence within their interior of a nuclear-like body and sundry vacuoles, as represented in the plate accompanying the article. Beyond this, all consisted of a homogeneous, interblending, and

adherent granular sarcode, showing in its attenuate condition that granule-circulation just described. The Foraminiferal nature of the organism and the accuracy of Mr. Carter's first deductions relating thereto, were now therefore established beyond dispute, and it has now, it may be anticipated, found a permanent resting-place among the arenaceous, and in this case adherent test-building Foraminifera represented by Dr. Carpenter's family of the Lituolida.

Mr. Kent then details the capture and digestion by the animal of the nauplian larva of a crustacean which still more clearly established its true nature, and describes the characters presented by the external test or skeletal portion.

Through the artificial preservation for several weeks of living specimens some knowledge of their developmental history was obtained, and every gradational step from the naked pyriform zooid to the test-constructing and matured condition was observed.

The Embryology of Sponges.-Mr. Kent, at pp. 139-156 of the same volume, records the results of an extended personal investigation of the so-called "ciliated embryos," or larvæ," or "reproductive gemmules" of sponges. Whilst Metschnikoff, Carter, Oscar Schmidt, F. E. Schultze, and Barrois agree with one another, and so far with Haeckel, in according to these bodies the existence of two or more distinct cellular layers, carrying with it the inference that sponges are true tissue-forming Metazoa, Mr. Kent considers the sponges to be compound colony-building, collar-bearing flagellate monads, exhibiting neither in their embryological nor adult condition phenomena that do not find their parallel among the simple unicellular Protozoa," and he regards" the so-called 'ciliated embryos' as the equivalent not of a single body or person, but as a special aggregation of innumerable individuals, to which collectively the title of compound ciliated gemmules' or 'swarm-gemmules,' may be most appropriately applied. The chain of evidence supporting this decision" follows, as the result of which Mr. Kent submits that the developmental manifestations of the ciliated sponge embryo make it clearly evident that we have here "merely a mode of increase, for a special purpose, by multiple fission differing in no essential manner from that common to Magosphæra, and the independent collar-bearing types, such as Salpingoca, and the majority of the Infusoria flagellata. That these bodies cannot in any way be compared with the true ova of the ordinary Metazoa is demonstrated not only by their inconstant form and character disassociated also with any act of spermatic fecundation, but from the fact that the segmentation of the primary unit gives rise to a morula-like aggregation which does not develop by the fusion of its constituent particles or blastomeres into a single germ-lamella or blastoderm, but into a number of distinct and independent unicellular zooids or units. The metazoic interpretation of the nature of sponges, as grounded upon the developmental manifestations of these same bodies, must likewise, as a consequence, be abandoned or otherwise be extended to the simple Monadina, Radiolaria and Catallacta, which produce a similar morula-like segmentation-mass, thus leaving the Protozoa in possession only of little more than an empty title. The true nature and

significance of the so-called ciliated embryos of the sponge, while not reconcilable with the proposed metazoic interpretation, becomes clearly intelligible on collating these organisms with the unicellular Protozoa. Regarded from this position, the identity of the ovate aggregation of separate units which constitute the so-called spongeembryo with the similar aggregation of units of the segmented monad, afterwards separated and dispersed as swarm-spores, is made apparent. This sponge-embryo is in this manner demonstrated to be merely an aggregation of swarm-spores held closely bound to one another throughout the process of development-a 'swarm-gemmule,' whose mission it is, in its aggregate condition, to lay the foundation of a composite sponge-stock similar to the one which gave it birth, and in manner identical with that individually effected by each motile swarm-spore of the solitary monad.

As a final demonstration of the protozoic nature of sponges, the multiplication of these organisms by the production of countless infinitesimal spores after the manner of the typical Monadina, has been determined. This spore-formation is brought about through the assumption by the matured collar-bearing zooids of a quiescent encysted state, accompanied or not by the fusion of two individuals. The spores produced by the breaking up into almost invisibly minute particles of the entire protoplasmic substance of the encysted zooids, are liberated in the substance of the syncytium; and within this matrix each spore develops again through an amoeboid or cytoblastic, and then simply flagellate, phase to an adult collar-bearing unit. The multiplication of the typical sponge monads or Spongozoa by the means of spores represents the constant and normal manner in which the growth and extension of the sponge-colony is effected; the aggregated masses of individuals or swarm-gemmules, liberated only at certain periods, representing a special development for the more extensive dissemination of the species."

Osmic Acid.-With reference to Dr. Pelletan's recommendation of osmic acid for the purpose of fixing Rotifers, Infusoria, &c., with their organs extended (see p. 189), the following note from the August number of the Journal de Micrographie' may be quoted :-"Osmic acid is a reagent the employment of which requires some precautions. It is very volatile, its vapour has a very disagreeable odour, is very poisonous, very irritating, and may cause serious injuries to the eyes. It is found commercially in the form of crystals, in small tubes hermetically sealed. The two points of the tube should be broken, and the crystals put into a known weight of distilled water. If the weight of the tube when empty is deducted from its weight when full, that of the crystallized acid is known, and consequently the strength of the solution, which can then be diluted with distilled water as may be required. The solutions may be preserved in flasks closed with sealing-wax, which can be softened by a heated metallic rod at the time of use. A little of the solution may be taken out with a pipette, and the flask closed again with the sealing-wax. Small quantities of the solution can be preserved for immediate requirements in stoppered bottles.