940 SUMMARY OF OUKRENT RESEARCHES RELATING TO 



Structure of False Gills of Pectinibranch Prosobranchs. * — M. F. 



Bernard has examined tlie so-called false gills in Cassis, Buccinum, Nassa, 

 Murex, and various other genera of pectinibranch gastropods. He thinks 

 ■we must consider the organ as formed of a series of folds of the internal 

 layer of the mantle. The space in the interior of each lamella is a lacuna 

 which communicates by a cleft with the large intrapallial lacuna which 

 extends under the false gill. The afferent branchial canal which extends 

 between this organ and the true gill is well provided with muscular walls 

 on the side of the latter ; but on the side of the false gill it is only separated 

 from the intrapallial lacuna by a spongy connective tissue perforated by a 

 large number of orifices by which the blood of the false gill passes to the 

 canal and thence to the heart ; the canal is not therefore strictly a vessel. 



A principal nerve, sometimes formed of several anastomosing bundles, 

 penetrates into each lamella where it gives off ramifications ; among these 

 are found multipolar connective cells identical with those found in the 

 true gills. The nerve has been easily studied by the aid of the double 

 chloride of ruthenium and potassium (or ammonium), which was found to 

 be more useful than hyperruthenic acid. By its means the fibres may be 

 seen to become gradually isolated and to terminate in large rods placed 

 among epithelial cells. 



The epithelium contains mucous cells, ciliated cells as in the gill, and 

 elements which end in a pretty long delicate rod. The basilar membrane 

 presents crests, folds, and thickenings directed along the courses of the 

 nervous ramifications, but there are never the double longitudinal thicken- 

 ings which are characteristic of the branchial lamellae. 



The muscular fibres are numerous and varied, and may, by their com- 

 bination, diminish the size of the blood-sinus, but their irregular arrange- 

 ment, and the presence of connective elements in the interior of the sinus 

 prevent our regarding the latter as a vessel. In some Strombid^ and in 

 Pterocera, the nerve bifurcates several times and branches in a fanlike 

 fashion. On the whole, the author regards the false gill as a sensory 

 organ formed by folds of the mantle in which there are a number of nerve 

 formations. In some of the higher forms the connective elements are so 

 arranged as to form a respiratory apparatus no less differentiated than the 

 gill-lamellae themselves. 



Renal Organs of German Prosobranchiata.t — Herr G. Wolff has in- 

 vestigated the structure of the renal organs of Paludina vivipara, Bithynia 

 teniaculata, and Valvata piscinalis. He has been able to detect the internal 

 orifice of the organ, though it is considerably degenerate. The ductus 

 renopericardialis appears to be least atrophied in Valvata, which so far 

 stands nearest to the pulmonate gastropods ; the well-developed cilia found 

 on its epithelial cells are wanting from Paludina and Bithynia. In 

 P. vivipara the duct is placed at the point where the renal organ opens into 

 what Leydig called the water-reservoir, and it is clear that the pericardial 

 orifice of the kidney is physiologically connected with the opening of the 

 kidney into the reservoir, since the muscular fibres which surround it are 

 connected with the sphincter which surrounds the other opening of the 

 kidney. The glandular organ of Bithynia has two openings which lead to 

 the exterior, one superior, and one inferior. The pericardial orifice is 

 placed near the upper of these. 



Oogenesis of Chiton.^ — M. P. Garnault has studied the development of 

 the ovum and its follicle in Chiton cinereus and Chiton fascicularis, and 



* Comptes Rendus, cv. (1887) pp. 383-5. t Zool, Anzeig,, x. (1887) p. 317. 



t Comptes Eendus, cv. (1887) pp. 621-3. 



