The spermatogenesis of Peripatus (Peripatopsis) balfouri. 345 



In the early prophases of the last spermatogonic mitosis the 

 chromatin granules arrange themselves evenly along a linin thread, 

 which is probably single and continuous. This corresponds to the 

 stage of the "dense spirem" or "continuous spirem"; to the continuous 

 linin thread has been given by me the term "linin spirem". Now my 

 observations show that in Peripatus very probably this linin spirem 

 remains continuous and unbroken, not dividing into segments, from 

 this stage on to the formation of the spindle in the 1st naturation 

 monaster. Next the chromatin along this spirem segregates into 28 

 rod-shaped bodies, the chromosomes ; but though the chromatin thus 

 segments the linin spirem remains continuous (Fig. 257). The only 

 portions of the linin spirem which can be seen are the inter-chromo- 

 somal fibres ; that portion of the linin spirem which forms the matrix 

 of each chromosome, and to which I have given the name "axial 

 thread", is hidden by the chromatin but is still present and is con- 

 tinuous with the inter-chromosomal threads. With the formation of 

 the monaster stage (Fig. 258) the 28 chromosomes become arranged 

 in the equator of the cell; but the linin spirem still persists intact. 

 In the following metakinesis (Fig. 259) each chromosome becomes 

 longitudinally split ; this produces a longitudinal splitting of the axial 

 linin threads, except a small portion of each of them which becomes 

 stretched out between two corresponding daughter chromosomes to 

 form a connective fibre (Fig. 259 C. F). That much can be actually 

 observed in the metakinesis. I could not directly observe the be- 

 havior of the inter-chromosomal fibres (compare the descriptive part 

 of the paper), but all the later relations would show that they too 

 become longitudinally split (as shown in Fig. 259). The metakinesis 

 then is not only a longitudinal halving of all the chromosomes, but 

 also a longitudinal halving of all the axial threads and probably of 

 all the interchromosomal fibres; so that the mother linin spirem divides 

 into two daughter linin spirems, one for each daughter cell, and each 

 daughter linin spirem is continuous like the mother linin spirem. In 

 this process it is to be noted that the only portions of the mother 

 linin spirem which do not become halved, are those portions which 

 go to form the connective fibres ; these later disappear (apparently 

 outside of the nucleus) , but without disturbing the continuity of the 

 daughter linin spirems. 



Just after metakinesis the daughter chromosomes wander to the 

 poles of the spindle (Fig. 259), in such a way that one end of each 

 chromosome points to the pole of the spindle, the other end to the 



