systems which connect the bulbs with the more distant parts of the brain, and, partly also, with one another. From the rich possession of nerves by Jacobson's organ in an eight-week old embryo, and their disappearance in older embryos, we may conclude that the organ is now in a rudimentary condition, as compared with what it was in ancestral forms. Eggs of Birds.*-Prof. Tarkhanoff records a very interesting inquiry into the structure of the eggs of birds. He finds that albumen of the eggs of the Insessores (ousel, canary, pigeon, &c.) notably differs from that of the autophagous birds (hens, ducks, geese, turkeys). When boiled it remains translucid; it is fluorescent; its rotation-power on the plane of polarization is feebler; when diluted with much water it does not give a white deposit, but only gives a feeble opalescent coloration to the water; finally it has a stronger basic reaction than the white of the eggs of the hen. It may, however, be transformed so as to become like it by various means, namely, the addition of neutral salts, or of bases, or of concentrated acetic and lactic acids, or even of carbonic acid. The most remarkable fact, however, is that the same result is also arrived at by incubation, and Prof. Tarkhanoff considers that the modifying agency in this case is the yolk; when moderately heated with yolk in closed vessels, during twenty-four hours or more, it is transformed into albumen like that of a hen's egg. As to the manner in which the yolk acts on it, it still remains unsettled; the supposition that the diffusion of salts is the cause of the change proved not to be true; and the cause must be searched for perhaps in the diffusion of gases. The interesting question, as to the albumen of hens' eggs not also undergoing the same stages of development within the ovarium, cannot yet be solved satisfactorily; but during his experiences M. Tarkhanoff observed once the most interesting fact that a small ball of amber introduced into the upper part of the ovarium occasioned the deposition of albumen around the ball, and the formation of a shell, that is, the formation of a quite normal egg with its chalaza, and other particulars of structure. This observation would thus strongly support the mechanical theory of the formation of the parts of an egg around its yolk. Chemical Composition of the Egg and its Envelopes in the Common Frog.t-P. Giacosa, to isolate the envelope, placed the eggs for some hours in lime water, whereupon the envelope dissolved while the yolk settled down to the bottom. The filtered solution, treated with acetic acid of 10 per cent., yielded a flocculent precipitate, which, after repeated washing with acetic acid and pure water, gave by analysis 52.71 per cent. C., 7.1 H., 9.33 N., 1.32 S., and 0.42 ash, whence the author infers the presence of a mucin. This substance resists putrefaction, and does not reduce copper salts till after boiling with dilute sulphuric acid. The author intends to study the products of this decomposition, but as he has not been able to detect the * Mém. Soc. Nat. St. Petersburg, xiii. (1883). See Nature, xxix. (1884) p. 461. Journ. Chem. Soc.-Abstr., xlvi. (1884) pp. 198-9, from Gazetta, xiii. p. 171. presence of any other bodies, he concludes that the enveloping membrane of frogs' eggs consists of pure mucin. From the oviduct of the frog he also succeeded in extracting a mucin, which though differing from the preceding in centesimal composition, nevertheless agrees with it in all other characters. Zoonerythrine and other Animal Pigments.-C. de Mereschkowsky gives the results of recent researches on zoonerythrine and other animal pigments. A list of the species in which that naturalist has noted the presence of zoonerythrine includes several members of each of the following, Coelenterata, Echinodermata, Vermes, Crustacea, Bryozoa, Tunicata, Mollusca, and Pisces, in all 117 species. Zoonerythrine is usually found in the superficial layer, but in some species it occurs in the muscular tissue. Various phanerogamous and cryptogamous plants also contain it. Numerous other pigments are enumerated. One group of these is characterized by the ease with which they can be transformed into zoonerythrine under the influence of certain chemical or physical conditions, such as elevation to the boiling-point, or the addition of a drop of acid; while another group is characterized by the impossibility of transforming them into zoonerythrine. Commensalism between a Fish and a Medusa.t-Referring to G. Lunel's paper on the union of Caranx and Crambessa, in which he speaks of the commensalism of fishes and Medusa as something doubtful and unknown, W. Macleay points out that the fact was well known to the Commissioners on the Fisheries of New South Wales, who in their report written nearly four years ago, alluding to the Yellow-tail, Trachurus trachurus, say :-"The very young fry have a most extraordinary and ingenious way of providing for their safety and nutrition at the same time; they take up their quarters inside the umbrella of the large Medusa, where they are safe from their enemies, and are, without any exertion on their part, supplied with the minute organisms which constitute their food, by the constant current kept up by the action of the curtain-like cilia of the animal." B. INVERTEBRATA. Annelid Commensal with a Coral.§-J. W. Fewkes records the fact of an annelid commensal with the coral Mycedium fragile. The worm occupies a calcareous tube, which, for the greater part of its length, is firmly fixed to the lower side of the coral. In a normal coral colony, the tube opens near the edge of the cupuliform disk of the young coral; the growth of the edge imprisons the worm-tube which, in time, becomes completely surrounded by the living coral. The worm and its tube grow also, and as the tube remains free at its orifice, the worm within is in free communication with the surrounding * Bull. Soc. Zool. France, viii. (1883) pp. 81–97. Cf. Amer. Natural., xvii. (1883) pp. 1301-2. + Abstr. Proc. Linn. Soc. N. S. Wales, 27th December, 1883, p. iii. See this Journal, ante, p. 35. § Amer. Natural., xvii. (1883) pp. 595–7. medium. Sometimes the coral covers in the mouth of the tube, and then the worm perishes: this, however, seems to happen very rarely. The presence of the worm causes an abnormality in the form of the coral, which, when alone, retains throughout life the discoid form of the young. Porites is another example of a coral with which worms live and its interior may be often seen to be perforated with wormtubes. Mollusca. General Account of the Mollusca.*-E. Ray Lankester has an exhaustive article on the Mollusca, which he arranges as follows::Phylum Mollusca. Class 2. Scaphopoda, e. g. Tooth-shell. Class 3. Cephalopoda. Br. a. Pteropoda, e. g. Hyalæa, Pneumodermon. After a general account of the Mollusca as a phylum of the Coelomata, the author describes a "schematic mollusc"; it has a head on which are placed a pair of short cephalic tentacles; the apertures of a pair of nephridia are seen to the right and left of the anus; the most characteristic organ is the foot (podium) which is probably genetically connected with the muscular ventral surface of the Planarians, and with the suckers of Trematoda. On the dorsal surface is the visceral hump or dome, protected by a shell, which is single, cap-shaped and symmetrical; the integument of the visceral dome forms a primary shell-sac or follicle. The wall of the body forms a flap or skirt-this is the mantle. Underlying this are the ctenidia or gill-combs, to which it is well to give a non-physiological name. Near the base of the stem of each ctenidium is a peculiar patch of modified epithelium, which tests the respiratory fluid and is persistent in its position and nerve-supply throughout the Mollusca; it is the olfactory organ of Spengel and may be definitely known as the osphradium. The term "gonad" is applied to the ovaries or spermaries, and it is pointed out that, at present, we cannot say whether the gonad was primitively median, or paired. The disposition of the nervecord is highly characteristic. A general sketch of the phenomena of development follows. The systematic review commences with pointing out the importance from a classificatory point of view of the radula. The Isopleura are divided into the Polyplacophora (Chitons), Neomeniæ, and Chatoderma; the two latter must be associated with the Chitons now that * Ency. Brit., xvi. (1883) pp. 632-95 (152 figs.). Hubrecht has discovered that Proneomenia has a radula and odontophore. In the division of the Anisopleura, Spengel's group of Streptoneura, or those in which the nerve-cords share in the torsion of the body, is adopted, and it is divided into the Zygobranchia, in which the organs of the left side do not undergo atrophy-such are the limpet (with regard to whose anatomy much information is given), Haliotis, and Fissurella; the second order is that of the Azygobranchia in which the left ctenidium and nephridium are atrophied; they are either creeping forms (Reptantia) like Turbo, Turritella, Cyclostoma, Dolium, Conus, and Buccinum, or Natantia like Atlanta and Pterotrachea. Spengel's name of Euthyneura is also adopted for those Anisopleura in which the tension of the visceral hump does not affect the nerve-cords; here we have the Opisthobranchia and the Pulmonata. Although the different members of the group of the Cephalopoda differ very greatly among themselves, they are all characterized by the "encroachment of the fore-foot so as to surround the head, and by the functionally important bilobation of the mid-foot. Following the example of his predecessor (Owen) Lankester enters into great detail as to the structure of the Pearly Nautilus. Various observations of general interest occur throughout the article; the most important is perhaps the description of the nature of the so-called proboscids; the different forms are described and supplied with characteristic designations; indeed the whole essay teems with suggestions of new terms. It will be noticed that the author now removes the Polyzoa and Brachiopoda from the Mollusca, being led especially by the observations of Caldwell on Phoronis to think that the supposed agreement of structure is delusive. Intertropical Deep-Sea Mollusca.-P. Fischer, working at the collections lately made by the Talisman,' finds Arctic molluscs at great depths in the intertropical regions of the Atlantic, and points out that the difference between the superficial and the deep fauna is such that the genera are different, that their reciprocal associations have no relation, and that if the remains of these faunæ, although contemporaneous, were to be fossilized, we should say that they belonged to different epochs or represented the population of two distinct seas. With the northern species are found forms that are unknown at present in the northern seas. As Lovén suspected would be the case, it was found that the bathymetrical limits of the northern forms increased as the equator was approached, and it would appear, therefore, that the temperature of the water has more to do with the distribution of marine animals than the intensity of light. A number of forms hitherto supposed to be peculiar to the Mediterranean, were found off the coast of Africa; and we may conclude that the number of species confined to that sea are small. The great depths of Antarctic seas must now be investigated. * Comptes Rendus, xcvii. (1883) pp. 1497-9. New Cephalopoda.*-A. E. Verrill, in a supplement to his Blake Report' describes, among others, the representatives of two new genera. Nectoteuthis is allied to Stoloteuthis, but he weakens the effect of his discovery by remarking that "some of the peculiar features of the arms and suckers may be only sexual." Opisthoteuthis is most remarkable for the posterior opening of the siphon and branchiæ, which is in correlation with the union of the head and body with the brachial membrane. Both of these new genera are founded on single specimens, and in neither case was the sex of the individual absolutely certain. Two new species of Octopus, O. punctatus and O. bimaculatus, are described in a succeeding communication; with regard to the former the observations of Mr. Dall are of great interest. "When angry, the horn over the eye is erected, the arms coil together, the eye dilates, and the body quivers with rage. The muscles keep up a squirming motion, but I have never seen any approach to the dark colour figured by Chenu as characteristic of the angry Octopus vulgaris of the Mediterranean, nor any such elevated longitudinal ridges. The suckers project or are retracted according to the mood of the animal; their outer edge expands when about to seize hold, and contracts after getting hold of anything. . . . It never willingly turns its mouth up, and when forced to do so clenches its arms, like a fist, over it. With death comes flaccidity and flattening. One with a body 8 in. in diameter had the arms 16 ft. long. They shrank much in alcohol." The second species, as represented by its largest known male, has the dorsal arms 325 and 390 mm. long from the mouth; the second pair 540 and 450 mm.; the ventral arms 500 and 490 mm. The diameter of the larger suckers of the lateral arms was 11 to 14 mm.; the body was 70 mm. long, and where broadest, 75 mm. ... Operculum of Gasteropoda.t-M. Houssay has investigated the question as to what part of the foot of gasteropods excretes the substance of the operculum, and how the growth of that organ is effected. The term columellar border is applied to that portion of the operculum which is found near the columella of the shell, and that of parietal border to the opposite edge. The internal and external surfaces of the operculum are not formed in the same way. In the latter there is a small transverse cleft, the walls of which are lined by a special epithelial layer, which soon dries in air and becomes of a horny consistency. The cells of the layer secrete a structureless material which gives rise to a hyaline membrane; this escapes by the cleft and becomes added on to the operculum; as these are successively laid down the outer face of the operculum is striated. The inner surface is clothed by an apparently homogeneous layer. The spiral form of the operculum seems to be due to the slight rotation to which it is subjected as the shell grows, and the consequent alteration in position of the columellar muscle. The organ in question is produced by a part only of the epithelium of the foot, and, while it has * Bull. Mus. Comp. Zool., xi. (1883) pp. 105-24 (6 pls.). + Comptes Rendus, xcviii. (1884) pp. 236-8. |