SPERMATOGENESIS OF TEXERRIO MOLITOR. 37 1 



was fair, though by no means typical, the mitochondria being 

 stained violet, the chromosomes a deep purple. 



In 1905 Miss Stevens investigated the spermatogenesis of 

 Tenebrio molitor (050), paying special attention to the X chromo- 

 some. Her only reference to the conjugation stage is one short 

 sentence: "A brief 'synapsis' or condensation stage occurs at 

 the close of the last spermatogonial mitosis." She gives one 

 figure of this stage and one of a slightly later stage, both drawn 

 from iron-haematoxylin material. The drawing of the condensa- 

 tion stage shows a dense mass of chromatin at one side of the cell. 

 The other figure shows what I have called the "large-loop" stage. 



These figures and the accompanying descriptions indicate that 

 Miss Stevens at that time supposed the conjugation to be of the 

 type described by her for three of the Coleoptera and two of the 

 Lepidoptera ('o6a) and for Diabrotica vittata, another of the 

 Coleoptera ('08). The type as described for these forms \vas 

 telosynaptic. The very short loops that appear in the synizesis 

 stage, "a prolongation of the last spermatogonial telophase," 

 later straighten out and unite end to end to form loops which at 

 first very often have knobs or slight irregularities at the point 

 where the two chromosomes have come together. These loops 

 then pass directly over into the diffuse spireme. 



The appearances in my material indicate a considerable diver- 

 gence from this type. 



In the spermatogonia of the meal-worm there are nineteen large 

 chromosomes and one small chromosome, making twenty in all, 

 as shown in metaphase in Fig. I. Figs. 2, a and b, show two 

 views of a spermatogonial telophase from a cyst surrounded on 

 three sides by spermatocytes. I have inclined to believe this 

 stage the last telophase preceding the maturation divisions. 



The next succeeding stage that I was able to find is shown in 

 Fig. 3 ; this cell came from a cyst in which every cell except the 

 one figured showed a dense closely massed clump of chromatin 

 at one side of the cell. This appearance is so usual and so well 

 known I did not think it necessary to show a figure of it. It is 

 very similar to the stages called variously "synizesis" and "con- 

 densation," and as in Miss Stevens's material, seems to follow 

 directly on the last spermatogonial telophase. There may be 



