464 BOTANICAL GAZETTE [june 



No suggestion of the spiral arrangement with the strands radi- 

 ating from a "Chromatinknoten" as described by Bonnevie (5) 

 has been observed. 



That the chromosomes retain their individuality and do not 

 break up into a network is claimed by Gregotre (15), Yamanouchi 

 (32, 33), Sharp (28), Overton (25, 26), Stout (29), Bonnevie 

 (5), and Lawson (19); this is also evident in Allium tricoccum. 

 Although the chromosomes become considerably vacuolate and 

 thus cause the net appearance, the individual members never lose 

 their entire individuality, as can be seen from the description and 

 drawings, and later, owing to a larger amount of chromatin material 

 and a more even distribution of it, the chromosomes form a more 

 or less continuous thread, the spirem. 



Little growth occurs during the later stages of the resting nucleus, 

 but when the chromatin mass starts to contract, it increases 

 slightly in size, but not to the extent claimed by Lawson (19); 

 that is, that the appearance of the contracted mass is due to the 

 growing away of the nuclear membrane. Comparison of figs. 8, 9, 

 10, and 11 1 will make this clear, as fig. n is a drawing of an entire 

 nucleus, the dimensions of the chromatin mass being considerably 

 less than that of figs. 7 or 8. It is not until the mass has con- 

 tracted extensively that the large increase in size of the nuclear 

 cavity occurs (figs. 10, n). Were it but an apparent contraction, 

 as Lawson (18) states, due to the inflow of karyolymph into the 

 nuclear cavity, the osmotic pressure would be decreased, not 

 increased, and the increase in size would be the result of the larger 

 amount of fluid that it must hold. 



As synapsis approaches, the two halves of the spirem gradually 

 approximate (figs. 9, 10, 11), the final step usually being accom- 

 plished during synapsis (fig. n); although even as late as the 

 stage shown in fig. 10 the act might not have been completed 

 along the entire length. This process corresponds to that 

 described by Gregoire (14, 15), Yamanouchi (32, 33), Overton 

 (25, 26), and Allen (i), although these investigators claim it 



1 Figs. 1-12 were made with a magnification of 3500, while fig. 12 has a magni- 

 fication of 2650, so that comparison of the latter with the former is not to be made 

 where questions of size are concerned. 



