Studies on Chromosomes. 



525 



briefly to record the fact that Archimerus, which agrees so closely 

 with Alydus in most other respects, differs from this and all the 

 above-mentioned forms in that the heterotropic chromosome fails 



k 



d 



/ 



FIGURE 3. 



Archimerus calcarator. a, Side-view of first division metaphase showing heterotropic chromosome 

 and m-chromosome bivalent; b, polar view of metaphase-group, first division; c, anaphase group, first 

 division, side view; d, late anaphase, first division; e, f, polar views of metaphase-groups, second 

 division, the former including, the latter lacking, the heterotropic chromosome; g, spermatocyte- 

 nucleus, prophase of first division, showing heterotropic chromosome (h\ the two separate m-chromo- 

 somes (m),and five of the six large bivalents; A, views of the chromosome-nucleolus(heterotropic chromo- 

 some)at different periods i,from the contraction-phase of the synaptic period; 2, middle growth-period; 

 3, 4, later growth-period (the last three showing central cavity); ;', spermatogonial metaphase-group. 



to divide in the first mitosis, passing over bodily to one pole and 

 dividing equally in the second mitosis, precisely as in the Orthop- 

 tera (Fig. 3, c, </). This fact, which at first I myself hardly found 



