30 SUMMARY OF CURRENT RESEARCHES RELATING TO 



The rate was about 3^ in. per minute on a smooth glass set vertically 

 in water ; almost equivalent to a refutation of the time-honoured saying, 

 " as slow as a snail." 



Development of Aplysia. * — D. Carazzi criticises Georgevitch's 

 account of this development. In the first place he states that that author 

 has mistaken the species, and that his specimens must have been eggs of 

 A. punctata Cuv. and not of A. depilans as stated. Second, he criticises 

 the method employed ; and finally states that Georgevitch has inverted 

 his eggs, placing the anterior region below, the posterior above, so that 

 he has called the small blastomeres A and B, instead of C and D as they 

 should be called. This cardinal error, according to Carazzi, vitiates the 

 whole research. 



Tectibranchs. j — J. Guiart gives a description of the structure of 

 Aplysia depilans and Philine aperta, and discusses the affinities (a) be- 

 tween Bulleidee and Aplysiidae ; (6) between Tectibranchs and Nudi- 

 branchs ; (c) between Tectibranchs and Prosobranchs. His general 

 views as to the phylogeny are expressed in this scheme : — 



Dermatobranchs 



Aplysiidre 



Pleurobranchs 



Acera 



BulleitisB 



I 



Acteon 



Prosobranchs 



Artaropoda. 

 a. Insecta. 



Metamorphosis of the Blow-fly 4 — Dr. F. Supino has made a fresh 

 study of the post-embryonic development of Calliphora erytlirocepliala. 

 We cite two conclusions : — (a) the supposed phagocytes of Koualevsky, 

 Viallanes, Bees, and others do not appear to act as such ; the destruction 

 of the larval adipose cells does not seem due to leucocytes ; or, in any 

 case, these elements are not indispensable in the j)rocess ; (&) the 

 imaginal adipose tissue is not developed at the expense of the muscle- 

 nuclei, but from mesenchyme cells, which, though at first scattered, 

 come to be regularly disposed as the foundation of the said tissue. 



* Anat. Anzeig., xviii. (1900) pp. 382-4 (2 figs.). Cf. this Journal, 1900, p. 6G6. 

 t Causeries Scient. Soc. Zool. France, 1900, No. 4, pp. 77-132 (4 pis. and 35 figs.). 

 J Bull. Soc. Entomol. Ital., xxxii. (1900) pp. 192-216 (2 pis.). 



