No. 2.] COMPARATIVE CYTOLOGICAL STUDIES. 313 



langere fadige Aufreihungen, deren Strange zu Schlingen gebo- 

 gen Oder geknickt sind." In these ova two kinds of nucleoli 

 may occur, namely, numbers of the small ones just described, 

 and a large one with dark contours, which has a central 

 vacuolar, granular portion, and is peripherally homoge- 

 neous ; but nucleoli also occur which are intermediate between 

 these two kinds. GeopJiiliis electricus : here are numerous 

 small, pale nucleoli and a large one, which has a finely granu- 

 lated core, and an outer homogeneous layer, the latter portion 

 consisting of concentric layers; further, he noticed the infundib- 

 ular structure first found by Balbiani on the outer surface of 

 the nucleus, though he remarks that it is especially apparent in 

 eggs in which post-mortem changes have commenced (!), and 

 concludes : "Wir haben es sonach beziiglich des Trichters mit 

 einer Ausbuchtung jenes Hohlraumes oder Lichtung zu thun, 

 welche von der Hohlung um das Keimblaschen herum in den 

 Dotter dringt." The basis of this infundibulum empties into 

 a space around the nucleus, and not into the nucleus itself (as 

 opposed to Balbiani's observations) ; Leydig also thinks that 

 particles of finely divided nucleoli penetrate separately out of 

 pores which are present in the nuclear membrane, and that 

 these particles, arrived in the cytoplasm, fuse together to form 

 a large " Ballen." Stenobothrus : in the ova of the proximal 

 portion of the tg% tube there are either numerous small nucleoli 

 or a dense mass of very fine granules ; in riper germinal vesicles 

 they are much larger and resemble somewhat the nucleoli 

 in the salivary glands of Chironomus ; masses of nucleolar 

 substance wander out of the nucleus into the cytoplasm. In 

 Pemphigus bursarius there is one compound nucleolus, with fine 

 radiating processes ; and in Meloe violaceiis there are numer- 

 ous nucleoli, each of which has the structure of the single one 

 of the preceding species. Gasterosteiis aculeattis: in the month 

 of May there are numerous germinal spots, sometimes densely 

 grouped, sometimes arranged in rows ; the gradual thickening 

 of the nuclear membrane takes place at the cost of nucleolar 

 substance. Triton taeniatus: the germinal vesicle at the end 

 of October contains numerous nucleoli of unequal size, many of 

 which are arranged in columns ; the peripheral ones probably 



