SPERMATOGENESIS OF THE MVR1OPODS. 153 



further to characterize them. One of the cross-shaped tetrads 

 :i'lv in ori< -ming itself in the plane of the spindle. Another 

 chromo-ome. o-ie of the rod-shaped ones, shows a much more 

 striking and fundamental peculiarity, in that it differs from all 

 of the rest "f the bivalent chromosomes in the plane of its divi- 

 -ion- in tin- fir-t and second spermatocytic mitoses. The ac- 

 orv ( hromo-ome shows still more striking peculiarities, differ- 

 in mi the others in its origin, valence, behavior in the propha-c, 

 n -l.nioii ID I!H- mantle fibers of the spindle and in its distribution 

 ID 1. 111 Dm halt of the resulting cells. 



All of i he t'.n i- enumerated above offer evidence which seems 

 cDiiclu-i\c thai tin- chromosomes of Scolopendra heros, during the 

 -]>i Tinato< \ ic stages ;ii least, must be considered as di-tinci 

 cntiiic-. each "tie possessing certain well defined peculiarities 

 \\liith .in .1- characteristic for any given chromosome of the 

 spermato. is are the peculiarities of a species of animals. I 



belie\e ih.it (Mutually in many animals it will be possible to 

 make tin- -tatenient still broader and to demonstrate the c<>n- 

 linniiN of the individual elements from cell generation to cell 

 generation. \V- \\ill. then, be able to say that, while in different 

 cell '0 -i icr.iti.>ii -or different conditions of cell activity, the appear- 

 .iii.e ,ni<l bch.i\ior of any given chromosome may be quite dif- 

 iit. jn-t .1- i- true of many animals in different stages of their 

 c\i-icin . . \ t in .1 -imilar cell generation any particular chromo- 

 -ome \\ill | iic-.nt the same appearance and will behave in the 

 -.line 111. inner. I believe that the condition described above is 

 inn- iii Scolopendra heros but several facts conspire to make it 

 impo ible D|' ph\-ical demonstration. 



The-e difficulties are mechanical difficulties and have to do 

 \\ith the -mall -i/e of the chromosomes in the spermatogonial 

 stages and the close aggregation of these elements in the karyo- 

 sphere <>t the growth period. The difficulties due to the small 

 >i/e ..t the chromosomes in the spermatogonial stages appeal - 

 in-iiriiionniable. and the only evidences of individuality which 

 the\ pre-cin ha\ e to do with their absolute constancy in numb-r. 

 and \\ith the very characteristic behavior of the acce ory it 

 being the only element which can be identified at all Mages. 

 \Ye might rea-on from this that because one of the elements 



