AMITOSIS IN THE WALKING-STICK. 9 1 



There is no visible difference in the nuclear division in the large 

 and in the small tubules, and, while nuclei from both kinds are 

 figured, a description of one will hold good for both. The size of 

 the nuclei of the larger tubules is much greater than of the smaller 

 ones. Each nucleus contains a number of chromatin granules, 

 held in a reticulum, and several nucleoles which stain with the 

 safranin of Flemming's triple stain and with the fuchsin of an acid- 

 fuchsin-methyl green solution. The nucleoles are of different 

 sizes and are scattered irregularly within the nucleus : in division 

 some pass to each of the daughter nuclei. The size of the nuclei 

 in each tubule varies considerably as does their position, some 

 lying with their long axis across and some with it parallel or 

 oblique to the tubule. Most of the cells are arranged with their 

 long axis parallel to the length of the tubule but they do not all 

 occupy this position. The nuclei generally divided parallel with 

 the tubule although some oblique ones were seen. 



At the commencement of division the nucleus first assumes 

 an irregularly oval outline very similar to the resting nuclei ex- 

 cept a somewhat greater elongation (Fig. 5). The nucleus then 

 narrows transversely (Fig. 2) until it becomes apparent that it is 

 dividing amitotically (Figs. 3 and 4). 1 An examination of nuclei 

 at this stage shows that the nucleoli are about to become fairly 

 evenly distributed between the two daughter nuclei ; all those 

 not near the center of the nucleus continue in or near their orig- 

 inal position while those near the center are pushed, as this part 

 grows narrower, into one or the other of the daughter nuclei. 

 As the central part becomes more of a connecting strand the two 

 main portions change their outline becoming more circular and 

 losing the elongated appearance they had in the earlier stage. 

 Just after the completion of division the daughter nuclei project 

 in a point towards each other showing where the connecting strand 

 has severed (Fig. 6). 



While most of the cells are binucleate it was found that a 

 number of cells contained but a single nucleus. All cases of 

 amitosis seen were found occurring in the nucleus of the uni- 

 nucleate cells. In the binucleate cells amitosis was never seen. 



1 J. B. Carnoy, " La Cytodierese chez les Arthropodes." La Cellule, Vol. L, 1885. 



