248 WM. REES B. ROBERTSON 



V autosome paired with, and separating from, rod-autosome 

 mates (pp. 221-222, 246-247). In germ-cell divisions preceding 

 synapsis the V autosome existed separate from the rod auto- 

 somes, but in divisions succeeding synapsis it separated again 

 from them, passing into one-half the spermatids while the rod 

 autosomes passed into the other half. I can think of no clearer 

 evidence than this that synapsis takes place — that chromatin 

 elements actually become associated two hj^ two. 



In the unequal homologous chromosome pairs of Tettigidea 

 parvipennis and Acridium granulatus, we have a third line of 

 evidence for synapsis. In one case an abnormal individual 

 was found having a deficient no. 4 chromosome paired with a 

 no. 4 of normal size (figs. 115, 120); in an other case, an abnor- 

 mally long no. 1 paired with a normal sized no. 1 (figs. 136- 

 147). I find that the members of these unlike pairs in the two 

 individuals exist apart in diploid series (figs. 136-140), together 

 in synapsis in the first spermatocyte of the germ cell generations 

 (figs. 141-143), and that they again separate from each other 

 at the first spermatocyte division (figs. 144-147). 



2. Admitting the fact of synapsis, are the conjugating elements 

 chromosomes, and are they individually identical with those of the 

 last diploid or pre-meiotic division? To prove this, one must 

 be able to trace the individual chromosomes from the telophase 

 of the last spermatogonial division to the prophase of the first 

 spermatocyte division. I have not done this in the cases de- 

 scribed in this paper. My evidence must, therefore, be indirect. 



Giglio-Tos ('08) and Granata ('10) look upon the chromo- 

 somes as being not permanent morphological structures, but 

 only temporary formations resulting from chemical processes 

 of some sort. They therefore believe that the individual chromo- 

 somes become disintegrated and disappear after the last sper- 

 matogonial division, that the chromosomes of the first spermato- 

 cyte are formed anew in half the fonuer number, each split 

 twice longitudinally, thus becoming tetrads for the maturation 

 divisions. Meves ('96, '07a), Fick ('07, '08) and Duesberg 

 ('08) likewise believe that the individuahty of the spermato- 

 gonial chromosomes is lost during this period. According to 



