BLACKMAN : THE SPERMATOGENESIS OF SCOLOPENDR.V. 15 



nuclear vesicle becomes more and more faint, until it finally stains less 

 strongly than does the cytoplasm immediately surrounding the nucleus 

 (Figs. 128, 130). That it is composed entirely of linin there can be 

 no doubt whatever, its non-chromatic character being shown both by its 

 general appearance and by micro-chemical tests. Here and there in this 

 lightly staining network are suspended coarse, deeply staining granules, 

 which are little larger than centrosomes. These are probably granules of 

 metaplasm deposited in the nucleus as reserve food material. Such gran- 

 ules are also found more or less numerously in the cy'toplasin outside the 

 nuclear membrane. They differ from centrosomes in various ways and cau 

 be distinguished from them readily. At this period, which, as stated, 

 I shall call the vesicle stage, the chromatin is deposited in a dense mass 

 around the accessory chromosome. This enveloping body, to which I 

 have given the name karyosphere, is situated at one side of the nucleus in 

 close apposition to the nuclear membrane. It is not a single element, but 

 is formed by the aggregation of all the chromosomes about the accessory 

 chromosome as a centre. The karyosphere is not homogeneous, as I be- 

 lieved at the time I wrote my first paper upon Scolopendra. In those 

 studies my observations were made with a magnification of 1000 diam- 

 eters upon sections Gf micra thick. In my later work sections 2 to 3 or 4 

 micra thick were also used, and the objects were observed under a mag- 

 nification of 1200, 1920, x or even 2G20 diameters. By means of this 

 increased magnification of very thin sections it was found that the kary- 

 osphere is entirely different in structure from what I at first believed. 

 It is a very complex mass of fine chromatin fibres closely enveloping a 

 solid chromatin body. Whether this fibrous, mass is composed of the 

 loops of one continuous thread (i. e. is a true spireme), or whether it is 

 in the form of segments, I am unable to state positively. However, I 

 believe the latter to be the case, for reasons which will appear later, 

 when I come to the description of the formation of the chromatin ele- 

 ments from this mass in the ensuing prophase. Often, in the thicker 

 sections in which the process of extraction of the haematoxylin has been 

 carried farther than usual, the karyosphere presents the appearance rep- 

 resented in Figures 19, b, 130. In those cases the mass is often bounded 



1 In obtaining a magnification of 1920 diameters, a j^ in. objective with a no. 8 

 ocular was used, and a beautiful clear image resulted. With a magnification of 

 2620 diameters the same ocular was used with a ^ in. objective. Here the re- 

 sults were not so satisfactory, and less reliance was placed on the observations. 

 However, the magnification of 1920 diameters was sufficient to show the structure 

 of the element well. 



