518 RECORD OF CURRENT RESEARCHES RELATING TO 



(h) There is no trace of an olfactory lobe in the early stages of 

 development of the olfactory nerve. 



(c) The olfactory nerve is a primary nerve comparable to the 

 segmental cranial nerves. 



The facts recorded concerning the development of the olfactory 

 nerve and olfactory organ, point towards the same conclusions as the 

 morphology of these structures, viz. that the latter is the visceral 

 cleft, that the former is the segmental nerve supplying that cleft in a 

 manner precisely similar to that in wliicli the hinder clefts are 

 supplied by their respective nerves, and that the Schneiderian folds 

 are gills ; conclusions which, if accepted, will considerably simplify 

 our conception of the segmentation of the vertebrate head. 



B. INVERTEBRATA. 



Digestive Ferments of the Invertebrata.*— The paper of Dr. 

 Krukenberg (of Heidelberg) on this interesting subject is reviewed in 

 the ' Archives de Zool. Exp.' 



In the most lowly developed forms (Myxomycetes and Porifera) 

 there are digestive ferments, of which the best developed is the peptic ; 

 in most Echinoderma the formation of the ferment is not fully 

 localized, and it seems possible that the nutriment may in them 

 undergo ferment action outside the intestine ; the liver of the As- 

 tei'ida is completely analogous to that of the Arthropoda or Mollusca ; 

 an analogous gland has been noted in the Holothurian Cucumaria 

 planci, and in the Echinid Toxojmeustes lividus and T. hrevispinosus ; 

 in some Vermes the thryptic ferment (isothrypsin) is different to that 

 of the Vertehrata, Arthropoda, and Mollusca, though probably iden- 

 tical with that of the Asterida ; the hepatic follicles of Aphrodite 

 have not this function ; and it appears that there is nothing in the 

 Invertebrata similar to the " stomach " of the Vertehrata. 



Mollusca. 



New Facts in the Anatomy of MoUuscs.j — Dr. H. von Jhering 

 contributes a short note on some recent discoveries he has made in the 

 anatomy of molluscs. 



He states that in the Nudibranckiata, urticating organs (Nessel- 

 elemente) occur, sometimes having the form of simple rods, as in 

 Turbellaria, sometimes having the complicated structure of a 

 Coelenterate thread-cell. They arise invariably in the interior of 

 ectodermal cells, and are formed in an urticating sac (Nesselsack), a 

 structure surrounded with strong muscular walls, and situated at the 

 extremity of the dorsal papillse. In many genera this sac is pro- 

 longed at its proximal or hinder end into another, thin-walled sac, 

 which is in close contact with the prolongation of the alimentary 

 canal extending into the jiapilla : in many cases, even, the two run 

 together, thus establishing a communication between the alimentary 

 processes and the urticating sacs. In these same genera, also, each 

 alimentary process opens externally by a small aperture at the apex 



* ' Arch. Zool. Exp.' (Lacaze-Duthiers), vii. (1878) No. 3, p. xxxi. 

 t 'Zool. Anzeigcr,' ii. (1879) p. 136. 



