"In the case of tidal marine pools and small fresh-water ponds, such as may easily be fished from the edge, a common ring net fitted with a muslin bag and attached to the end of a walking-stick will answer every purpose. This may be worked to and fro amongst the weeds or in the clear water, and the results, when cleared from coarse debris and extraneous materials, may either be put at once into spirit, or, if it is wished to keep the Entomostraca alive, into water, fresh or salt, as the case may be. Marine surface-swimmers may be taken in a similar way by working the net from the side of a boat, or a tow net may be thrown over and attached to the boat by a cord. A tow net put overboard from a vessel anchored for the night in a tideway will often be found in the morning to have made good captures. And it may be noted that surface net gatherings made during the hours of dusk or darkness are commonly of much greater interest than those taken in daytime; it seems certain that many marine Crustacea which are found near the surface at night recede towards the bottom on the approach of daylight. . . . The washing of fronds and roots of Laminariæ, which may be dragged up by means of the hooked grapnels used on many coasts by kelp-burners, often affords multitudes of Copepoda. The weeds should be washed by agitation in a large tub of sea-water, and when the operation is completed, the water, after being allowed sufficient time-a few seconds only for the subsidence of coarse material, is to be poured off through a muslin net, on which the Copepoda, and probably numerous other swimming animalcula, will be intercepted. These may be cleaned while in the net by repeated douches of sea-water. The products of the dredge, sand, mud, gravel, shells, &c., should be treated in a similar manner before being thrown overboard. I have no doubt that this method of procedure offers by far the best chance of extended acquaintance with microscopic life of the sea-bed, and that numberless new species and interesting forms of life may be discovered by its

means.

...

The preservation of specimens is probably best effected by alcohol in the form of rectified or methylated spirit, but this agent has the disadvantages of destroying many colours, and of rendering the animals opaque by coagulating their albuminous tissues. Still, among the numerous solutions which have from time to time been recommended, none are on the whole so convenient or efficient. Perhaps the next best is a solution of chloral hydrate (twelve grains to a fluid ounce) in camphor water. As microscopic preparations, Copepoda are best mounted in some gelatinous medium containing a very small quantity of glycerine. Treated in this way, mountings will keep in perfect condition for many years-eternally for anything I know to the contrary-without the trouble of cementing round the edges of the glass cover. Before dissecting Copepoda for microscopic examination, they should be macerated for a few hours in a solution of caustic potash; the fatty and granular tissues are by this means removed and the details of structure rendered clearly visible; the dissection is easily performed under the microscope with fine needles, either with or without the help of an erector."

Zeiss's New Oil-immersion Objective.—Mr. A. Schulze “finds the optical qualities of this new lens in every respect equal to that of the, the angular aperture being about the same. The working distance is about one-thirtieth inch, and the magnifying power with a Ross A eye-piece fully 580 diameters. The field is perfectly flat, and the brilliancy and definition leave nothing to be desired, whilst the resolving power is extraordinary. All the finer diatomaceous tests, such as Amphipleura pellucida, &c., are resolved with the greatest case and with the utmost distinctness; and although I have hitherto failed to see both with the and the oil-immersion lenses more than with Powell and Lealand's excellent new formula, or some other firstclass water-immersion lenses, yet I see everything better and easier than with the latter. For the resolution of the markings on diatoms no better lenses could be desired than these oil-immersion lenses. . . . It is to be regretted that Professor Abbe and Mr. Zeiss deem it inadvisable to undertake the construction of microscopical objectives of yet higher power on the oil-immersion principle. This they do, however, both on account of practical difficulties in the production of still smaller lenses, and because no greater angular aperture could be gained than those of the ordinary largest angled water-immersion lenses."*

Theory of the Action of Bacteria in Anthrax.-In applying the data furnished by the experiments communicated to the Academy to the comparative study of the lesions which I have observed in different species of animals, I consider that it is possible to deduce from them a general theory of the action of bacteria introduced into an organism. The following is a summary of the theory:

Anthrax is due to the existence of a parasite which lives and is reproduced in the blood and fluids of living animals, which acts through its physical qualities, and through the substances which it secretes or exudes, or the formation of which it provokes; these substances are soluble, and possess inflammatory properties more or less intense according to the animals which nourish the bacteria. The difference in activity of the phlogogenic matter has not yet been explained: it is possible that it depends on the peculiar properties of the blood of the animals in which the parasites are developed, but some experiments, unpublished as yet, lead me to think that they may be owing to polymorphism.

When the bacteria produce a matter which is only slightly inflammatory, they act more especially by their physical properties, and cause death by the obliteration of the capillary vessels of the essential organs; such is the case with the rabbit, the sheep, and the guineapig, where these lesions are almost exclusively met with. To the more intense phlogogenic properties correspond vascular lesions of another order; the rupture of the capillary vessels and effusions of blood more or less considerable which exist simultaneously with the vascular obliterations, as is seen sometimes in sheep, and always in the horse and the ass. Lastly, the inflammatory properties may predominate, and

*English Mechanic,' vol. xxviii. p. 144.

death take place, when the number of the bacteria is relatively inconsiderable; the vascular ruptures then become of extreme importance; they are found especially in the walls of the heart of the dog.

It now remains, in order to complete this theory, to examine and explain the lesions of the lymphatic system. The following are the facts which have been derived from my experiments:

Three cases are possible:

1. The Anthrax was transmitted by inoculation to an animal which died without showing vascular ruptures.

2. The Anthrax was transmitted to the animal by injection direct into a vessel.

3. The Anthrax was transmitted either by inoculation or by intravascular injection to an animal which in the course of the malady showed more or less numerous vascular ruptures.

In the first case researches made on the fresh or hardened ganglia and by means of sections, showed no bacteria except in those situated in the course of the lymphatics, proceeding from the inoculated spot, where they were found in immense numbers.

In the second case no ganglion showed the presence of bacteria in the sinus; the only ones met with were contained in the blood-vessels of the follicles.

In the third case all the ganglia situated in the course of the lymphatics, proceeding from the points where the vascular ruptures existed, were gorged with bacteria; the infiltrations in the neighbourhood of the rupture showed heaps of them, formed of long entangled filaments, and the ganglia had a quantity of them in their sinus, which augmented with the age of the rupture.

These three cases are easily interpreted; they are reducible, in fact, to one. The mode of action of the bacteria is always the same. Take the first (that of inoculation) as a typical case.

When an animal has been inoculated, from that moment until its death it constantly shows the presence of bacteria in one or other parts of its economy-not latent bacteria in the state of the germ, but entire and articulated, and visible to the microscope. They are always found in the connective tissue adjacent to the inoculated spot, and their number is greater in proportion as the period of inoculation is distant from that of observation. The infiltration or oedema which they provoke, is propagated in the direction of the lymphatics which collect and convey them to the ganglion. They penetrate this organ, as do all finely pulverized solid substances, as red-lead injected under the skin and tattoo powders; I have found them in considerable numbers (about ten in the field of the microscope), five hours after an inoculation has been made, at two centimetres distance from an axillary ganglion, in the pulp of this ganglion. Once in a ganglion they multiply, produce inflammation, and a more ready discharge of the substances inclosed in the lymphatic sinus; their multiplication by elongation is also a mode of progression; they finally issue forth through the efferent vessels and reach the following ganglion, or rather the blood-vessels, where they multiply rapidly and where they

remain.

From the instant that the bacteria penetrate into the blood (by taking the blood of a rabbit inoculated 72 hours previously from three punctures made in the inside surface of each fore-leg, and injecting fifteen drops of it in the jugular of another rabbit, I caused the death of the latter) the phenomena are as though the injection had been made in the vessels, that is, as in the second case, allowance being made for the parasites constantly supplied by the ganglia which were the first receptacles.

Finally, in the case in which vascular ruptures supervene after the penetration of the bacteria into the blood, each rupture lets a greater or less number of bacteria escape, which there act as true, deep inoculations, which are followed by the same disorders as in subcutaneous inoculation, that is to say, infiltration, penetration into the ganglia, and return to the blood. But the disorders in this case are so numerous and severe that the animal dies before the capillary emboli are formed.

The knowledge of these facts may throw some light on the mode in which the bacteria penetrate in the case of spontaneous Anthrax; it enables us to determine in what part of the economy and through what channel the parasites are introduced.*

Onchopora hirsuta.-Mr. W. H. Weightman, of the Liverpool Microscropical Society, has shown that, besides the common tubes, described and figured by Mr. Busk in the Quarterly Journal of Microscopical Science' for 1855, there are also at the base of the lowest internode a number of radical tubes, which Mr. Busk seems to have overlooked. They are each upwards of one-tenth of an inch in length, hollow like the others, but spirally twisted, and not jointed. The extremity of each of these radical tubes is dilated, and of a crozier-like form, and of a much darker colour than the shaft. Within the crozierlike tip there appears to be a dark secretion, which in the living condition was probably fluid, but the purpose of which he is quite ignorant of.

The calcareous cell of Onchopora is somewhat granular in substance, and is minutely punctured, and acts with some degree of energy on polarized light, but not so much so as the corneous tubes, which are quite brilliant when viewed with polarized light; the radical tubes are somewhat less so.

Spore Nomenclature. In regard to an article on this subject in the Bot. Zeitung,' by Messrs. A. de Bary and E. Strasbürger, the 'Bulletin' of the French Botanical Society (vol. xxv. p. 32) says:-"The Acetabularia furnishes a new example of conjugation between zoospores, interesting because of the terminology it gives the authors an opportunity of proposing. The biciliated and sexual antherozoids which are capable of copulation receive from them the name of ' gametes,' and the products of their copulation that of zygote,' instead of isospore or zygospore. They are anxious to remove from this name the rootspore, reserving this term for the reproductive body which does not result from a fecundation."

* M. Toussaint, in Comptes Rendus,' vol. lxxxvi. p. 978.

The Causes of Buzzing in Insects.-The number of Comptes Rendus' for 7th October last contains a note by M. Jousset de Bellesme on M. Perez's paper on this subject which appeared in an earlier number, and which is translated at p. 276. The note is in substance identical with that which is quoted from the Times' at p. 278, and as, although somewhat more precise, it includes no additional facts, it is unnecessary to reproduce it here. A translation appears in 'Annals and Mag. of Nat. Hist.' for November.

The Germ Hypothesis of Putrefaction.-Dr. B. W. Richardson, F.R.S., delivered during the present year at the Society of Arts a series of six (Cantor) Lectures on Putrefactive Changes and on the Preservation of Animal Substances." The lectures concluded with a reference to the Germ Hypothesis, of which the following is an abstract :

This has been very differently treated by different authors. On one side it has been subjected to derision, on the other extolled to childish adulation. It may be said to have started with the observation of Redi, that the exclusion of dead animal matter from something in the air, which could apparently be filtered out of the air, arrests putrefactive change as it might arrest the introduction of the ova or germs of other living forms in the same substance. We have seen in our experiments that exclusion of air does, for a time, under some circumstances, interfere with commencing putrefaction.

This looks like truthful demonstration. Yet still it is a very easy thing to oppose the hypothesis altogether. We can show, that animal tissue decomposes in the closest chamber; when imbedded in hard paraffin; when coal-gas or other negative gas takes the place of air. All these facts indicate that air is not wanted either to act itself, or to convey particles or germs.

But it may be urged on the side of the hypothesis, that the dead animal substances, before the time when they were subjected to these exclusive tests, had been exposed to the infection of germs.

To this there is an experimental answer. Here are specimens which after having been subjected to the air itself, under pressure, had not decomposed; and others which have been exposed to the air, but because they are charged with a small part of a salt, or gas, or vapour, have not decomposed. Thus a substance may be exposed to the air and may not change. All our salted provisions may be used as arguments in support of this truth.

There will again be a ready answer to suit the hypothesis, namely, that under such conditions germs cannot live. The conditions are fatal to life in any form. How can germs live in cyanogen, or sulphurous acid, or under atmospheric pressure, beyond what is natural?

The answers are plausible, and the germ hypothesis might be defended possibly on them if there was nothing else to be said. But there is more behind. We can arrest life in action and still have decomposition. If I were to put a firm ligature round one of my limbs, and so completely cut off the supply of blood, I should do the

* Vol. lxxxvii. p. 535.