444 SUMMARY OF CURRENT RESEARCHES RELATING TO 



In Vivipara they are situated in the wall of the auricle, thus recalling 

 the intercardiac nephrophagocytes of bony fishes. Finally, in the three 

 families of Bulleidae (except Scaphander), Pleurobranchs, and Doridiidae, 

 there is a large and well-defined phagocytic organ which is abundantly 

 vascularized by the aorta. It recalls the organs of various Insects and 

 of Scorpionidffi. In those Molluscs in which it has not been possible 

 to demonstrate fixed phagocytes (primitive Lamellibranchs and aquatic 

 Pulmonates) it is probable that they occur, but are so sparse and _ so 

 inconstant in situation that they cannot be distinguished from wandering 

 amoebocytes. 



In all cases the fixed phagocytes, whether imprisoned in a network 

 of connective tissue or applied to the walls of lacuna?, are small amoeboid 

 cells exactly resembling free amoebocytes. Mitosis, effecting replacement, 

 rarely occurs (gill of Cephalopods, auricle of Vivipara) ; it may therefore 

 be concluded that worn-out elements are replaced by free amoebocytes 

 which settle down and become fixed phagocytes. 



From the point of view of function, the phagocytic apparatus of 

 Molluscs is of considerable interest : the papilla? of the left kidney of 

 Trochidse, the folds of the single kidney of Monotocardia, the gills 

 and the appendix to the branchial heart of Cephalopods, the nodules of 

 the hepatic arterioles of various Lamellibranchs, possess the unexpected 

 property of prephagocytic agglutination ; that is to say, the floating 

 particles in the blood-fluid are retained, fixed, agglutinated at the 

 very spot where later they will be ingested by the phagocytes. In this 

 way the organism gets rid of what encumbers the plasma almost instant- 

 aneously, and long before the phagocytes have time to intervene. An 

 analogous process is known in Synaptids and Sipunculids ; the floating 

 particles in the ccelomic liquid are rapidly agglutinated by a vibratile 

 mechanism (ciliated urns), and the phagocytes play their part later. 



a. Cephalopoda. 



Nervous System of Myopsidse.* — Boris Schkaff has made a careful 

 study of Loligo marmoree and Sepiola rondeletii in regard to the details 

 of the nervous system. He describes the central nervous system or 

 " brain " with its four component ganglia (cerebral, brachial, pedal or 

 infundibular, and visceral— of which the brachials are most distinctly 

 paired) ; the connexions between cerebral and pedal, pedal and visceral, 

 brachial and pedal, visceral and brachial, cerebral and brachial ; the 

 nerves o-iven off from the cerebral, visceral, pedal, and brachial ganglia ; 

 and the° sympathetic system, which consists of three ganglia connected to 

 one another by commissures and also with the central nervous system, 

 namely— the superior buccal, the inferior buccal, and the gastric. 



y. Gastropoda. 



Abyssal Fresh-water Snails of the Lake of Geneva.-f— W. 

 Roszkowski has made a minute study of the shells, teeth, and repro- 

 ductive organs of Limnsea profunda and L. abysskola from the depths 



* Zeitschr. wiss Zool., cix. (1914) pp. 591-630 (3 pis.). 

 t Rev. Suisse Zool., xxii. (1914) pp. 457-539 (4 pis.). 



