368 EDMUND B. WILSON 



A process of this type was long since describe.d by Janssens ('01) 

 in both the spermatogonial prophases and the pre-synaptic nuclei 

 of Triton (figs. 27, 67), where it somewhat resembles the resolu- 

 tion into threads of the 'nucleoli' of the germinal vesicle of the 

 same animal, as earlier described by Carnoy and Lebrun ('98). 

 A process more or less similar was described by the Schreiners ('06, 

 '08) in the post-spermatogonial (pre-synaptic) stages of Tomop- 

 teris, by Pinney ('08) in the sperma'togonial prophases of Phryno- 

 +.ettix, and especially by Davis ('08) and more recently by Brunelli 

 ('11) in the pre-synaptic stages of Chortophaga, Tryxalis and other 

 grasshoppers ; Gregoire describes a similar process in plant-cells, 

 first in the somatic cells of the root-tip in Allium ('06, p. 330), 

 later in the pre-synaptic sporocyte-nuclei ('07, p. 391). The 

 analogous relations discovered by Bonnevie and other recent 

 observers are referred to beyond. 



In Oncopeltus as the process begins, the pale chromatic mass'es 

 become looser in texture and more ragged in contour, and each of 

 them gradually assumes the appearance, though somewhat 

 vaguely, of a closely convoluted thread (figs. 52, 53). In the 

 stages that follow (figs. 54, 55) the coiling becomes looser, so that 

 contorted or spiral threads are clearly evident, and at the same 

 time the massive bodies progressively disappear from view. These 

 stages unmistakably show the nature of the process that is tak- 

 ing place. It is now clear that each of the original compact masses 

 (excepting the sex-chromosomes) has resolved itself into a tightly 

 convoluted thread, which is uncoiling to form a leptotene-thread. 

 The spiral or contorted course of the threads is still very evident 

 when the massive bodies as such have disappeared from view 

 (fig. 55), but is finally lost in the completed leptotene-stage (figs. 

 56 to 59) . In Lygaeus the process is closely similar and requires 

 no separate description. Figs. 71 and 72 show two nuclei in 

 Stage b, in each of which twelve of the paler masses can be 

 counted (not all shown in the drawing), while the X- and F-chro- 

 mosomes are conspicuously seen. Whole cysts full of these nuclei 

 are seen in nearly all of my sections. Figs. 73 a and 73 b show 

 two early leptotene-nuclei of this species after the unravelling is 

 completed. 



