34 SEXUAL REPRODUCTION IN CERTAIN MILDEWS. 



endeavor to follow the paths of the individual threads we find them 

 either straight or wavy in outline, and not infrequently threads are found 

 which bend sharply this way and that, following no definite direction. 

 Such threads are, however, relatively few and never abundant enough 

 to interfere with the general appearance of a radiating system centered 

 on the central body. Fig. 34 shows a section cut from one side of a 

 nucleus, so as to include only three chromatin strands with fragments 

 and cross-sections of others. In composition the threads appear lumpy 

 or finely granular, and hence of quite irregular thickness and density, 

 since the nodules are by no means of equal size. They probably consist 

 of chromatin granules embedded in and connected by a less stainable 

 linin, though the distinction of chromatin and linin can scarcely be made 

 out at this stage. The main threads do not apparently anastomose, 

 though they are occasionally found crossing each other. They are, 

 however, connected by lateral fibrillar or granular extensions which are 

 extremely delicate and quite numerous, so that in sections showing the 

 entire nucleus (fig. 32) the more prominent threads appear almost as if 

 embedded in a very faintly blue-stained ground substance. In fig. 34 

 the antipolar ends of the strands seem very definite, but this is probably 

 due to the fact that they are cut off in sectioning. In figures showing 

 the entire nucleus (figs. 32-34) , and especially in the smaller nuclei of 

 a slightly earlier stage (fig. 31), it is plain that the farther one follows 

 the threads from the central body across the diameter of the nucleus the 

 more difficult it is to distinguish them. In the nuclei prior to their 

 fusion it is impossible to trace the threads across the entire diameter of 

 the nucleus. They seem to fade out and lose their identity in a less 

 strongly differentiated granular*and thready mass, whose structure and 

 relation to the main chromatin strands is not easy to make out clearly. 

 The whole system of threads seems to pass over very soon (in fig. 31) 

 into a less differentiated granular reticulum composed of deeply stained 

 chromatin granules connected with abundant, more faintly stained 

 fibrillse, which seem almost to form a ground substance. The fibrillse 

 resemble closely the faintly stained fibrous material which connects 

 the threads nearer the center. This condition in the antipolar portion 

 of the nucleus doubtless represents more nearly a resting condition oi 

 the nuclear material in which the chromatin is more irregularly scat- 

 tered in the nuclear cavity, but is still connected definitely with the 

 central body. 



The appearance of the chromatin in the resting nuclei in the myce- 

 lial hyphae and the cells of the perithecium (figs. 23, 24) is very similai 

 to that which we find in the antipolar region of these nuclei of the 



