380 ■ EDMUND B. WILSON 



torted, more or less interrupted granular threads, which often 

 seem to branch more or less. These nuclei show a certain resem- 

 blance to the pre-synaptic leptotene-nuclei of Stage d; but both 

 their position in the testis and their structure render a confusion 

 between these stages impossible. When the process is completed 

 the threads are greatly diminished in staining-capacity, seem to 

 branch more freely, and in Oncopeltus and Lygaeus often give 

 almost the appearance of a network with thickened nodes (figs. 

 66, 67, 97). In Largus, however, the threads remain more in 

 evidence, and the nuclei do not so nearly approach the 'resting' 

 condition (fig. 104). 



At the height of this stage it is, I believe, quite impossible to 

 distinguish the individual chromosomes (bivalents) or to analyze 

 exactly the composition of the nuclei. I nevertheless incline to 

 the conclusion that the autosomes do not actually lose their 

 identity at this time. The phenomena which follow in Stage h, 

 especially as shown in Protenor, give considerable reason to con- 

 clude that the prophase-figures are already formed in the diffuse 

 stage but are lost to view by their intricate extension, contortion 

 and interlacing. In Euschistus, as recently described by Mont- 

 gomery ('11), the confused period is much less marked; and this 

 observer believes that the bivalents may be individually recog- 

 nized at every period. In Tomopteris and Batracoseps the con- 

 fused period is entirely omitted. 



In the condition described the nuclei remain throughout the 

 greater part of the growth-period. In Oncopeltus the sex-chro- 

 mosomes remain always spheroidal or ovoidal (photos. 11, 16) 

 and apparently undivided. In Lygaeus both sex-chromosomes 

 (of which a more detailed account is given at p. 384) are rod-like 

 and longitudinally split (photos: 13 to 15). In Largus the X-chro- 

 mosome is spheroidal but often shows a small but very distinct 

 central cavity. In all these forms the plasmasome is conspicuous 

 throughout, and attains its greatest size in this stage. In Onco- 

 peltus and Lygaeus the chromatin undergoes no contraction dur- 

 ing this period. In Largus, on the other hand (as in Pyrrhocoris, 

 Alydus and some others) the latter part of this period is charac- 

 terized by a very marked second contraction-figure or synizesis. 



