666 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Salivary Glands of Pulmonata.* — llina Monti describes the struc- 

 ture of the salivary glands of terrestrial Gastropods, distinguishing the 

 stroma of fibrillar connective-tissue and the parenchyma of mucous, 

 transparent, and granular cells. He contrasts the resting with the active 

 phases, and notes the absence of any hints of mitosis. 



Albumen- gland of Snail.f — Dr. G. Paravicini finds that this gland 

 exhibits profound changes both in form and structure in the course of 

 its development. It is at first unciniform and secondarily liuguiform. 

 It arises from the same embryonic stratum as the prostate gland. The 

 occasional appearance of supernumerary lobes in the adult is to be in- 

 terpreted as the persistence of a transitory embryonic state. 



Development of Aplysia.J — P. M. Georgevitch has studied the earlier 

 stages in the development of Aplysia depilavs, with special reference to 

 the origin of the mesoderm. As in many molluscs, a vitelline membrane 

 is absent. If at the four-cell stage the two cells of the animal pole bo 

 called A, B, and those at the vegetative pole C, D, and the nomenclature 

 be preserved throughout the divisions, then the primitive mesoblasts are 

 2 d and 2 c, and appear at the 12-cell stage. In their origin these cells 

 are closely similar to the mesoblasts of Polyclades, and by their division 

 they give rise to the mesoblastic bands. The author compares in detail 

 his figures and results with those of other previous observers, and in his 

 summing-up maintains that it is now proved that the mesoblast arises 

 in Aplysia after precisely the same fashion as in other molluscs. At 

 the same time the author's work on Aplysia accentuates the resemblance 

 between Mollusca and Polyclades in regard to the origin of the meso- 

 blast. 



5. Lamellibranchiata. 



Pelecypoda of the Chicago Area.§— Mr. F. C. Baker has prepared 

 the first part of the Chicago Natural History Survey, which deals with 

 the Pelecypoda. After a general introduction discussing molluscs in 

 general, methods of collecting and preserving, the features of the area, 

 and so on, the author proceeds to a systematic survey of the species. 



Sexual Dimorphism in Lamellibranchs. || — A. Ostrooumotf notes 

 that it is commonly stated that in Unto alone among Bivalves is there 

 any trace of secondary sexual characters. He has, however, found that 

 in Aslarie sulcata Phil, the females have the edges of the valves toothed, 

 while in the males they are smooth. 



Arthropoda. 

 o. Insecta. 



Middle Ocellus of Insects.1T — Chujiro Kochi points out that if the 

 middle ocellus in the adult insect, which Leydig and Brandt long since 

 showed to be double, is formed from the fusion of two ocelli once 

 separate, one might expect to find traces of two pairs of ocelli in 



* Read. 1st. Lombardo, xxxii. (1S99) pp. 534-5. f Tom. cit., pp. 918-23. 



% Anat. Anzeig., xviii. (1900) pp. 145-74 (30 figs.). 



§ Bull. Chicago Acad. Sci., No. iii. (1S9S, received 1900), 130 pp. and 27 pis. 



J Zool. Anzeig., xxiii. (1900) pp. 499-500. 



M Amer. Net., xxxiv. (1900) pp. 041-3 (1 fig.). 



