MUSEUM OF COMPARATIVE ZOOLOGY. o4o 



results, as far as regards Blatta, have been given in connection with the 

 review of his preliminary article (p. 289), and I will here call attention 

 to only one or two points dwelt upon in this ultimate paper. 



The nuclei of the "great germ cells" exhibit, after the employment 

 of acetic acid, numerous dark granulations which are united to each 

 other by fibres, — strung on the latter, as it were. These fibres may 

 constitute an irregular net work, running through the whole nucleus, or 

 they may take a quite regular, bush-like form. In the latter case they 

 arise from a point of the nuclear membrane about which granules of the 

 cell protoplasm are grouped. In clusters of neighboring nuclei these 

 points are turned toward each other, a fact which leads to the conviction 

 that a process of nuclear multiplication takes place with these " great " 

 cells. This opinion is strengthened by finding two such nuclei still 

 connected by fibres. After these "great" cells had become isolated 

 from each other, the nuclear metamorphosis was followed in the living 

 cells, as far, at least, as to establish a fibrous nature for the elongated 

 oval nucleus. Occasionally an equatorial thickening was also visible. 



There is little to be seen in his figures of a central area, though the 

 radial structure is well shown in some cases. (See Taf V. Figs. 14, 17, 

 op. cit.) 



The daughter nuclei arise by a diff'erentiation out of the dark homo- 

 geneous nuclear plates (Kernplattenkorper). This diff'erentiation is to 

 be considered as most probably brought about by the accumulation of 

 fluid between an external layer (nuclear envelope) of this dark, homo- 

 geneous body and its central portion (nucleolus). This originally single 

 nucleolus suffers a disintegration into a number of parts, each still con- 

 nected with interzonal filaments. Nothing like a cell plate is to be seen. 



The very interesting statement is made that sometimes masses of 

 protoplasm containing two nuclei undergo division. This was observed 

 to take place in one or the other of two ways. In both methods the 

 two nuclei divide at the same time and give rise to two spindles having 

 parallel axes ; in one case the protoplasm is grouped about the two 

 daughter nuclei, which occupy corresponding ends of their respective 

 spindles, as if about a common centre ; in this case two binuclear cells 

 result ; in the other case the components of 07ie set of daughter nuclei 

 may separate from each other and become the centres of two smaller 

 cells. In the latter case the result is one binuclear and two uninuclear 

 i cells. 



j Biitschli draws the conclusion that a common cause, resident only in 

 the surrounding protoplasm, aff'ects the division in these cases. 



