508 CAROLINE BURLING THOMPSON 



men, show that these organs are closelj^ invested by the masses of 

 the fat body. The testis is divided into many lobes opening at 

 their lower or proximal ends into the central space which leads 

 into the upper enlarged end of the vas deferens. The testis lobes 

 are enveloped by a dehcate outer layer of connective tissue which 

 also extends as septa into the interior, dividing each lobe into 

 separate portions, in which lie the groups or cysts of the male sex 

 cells. The youngest sex cells, the spermatogonia, form a terminal 

 zone at the upper, distal, ends of the lobes; proximal to these may 

 be seen zones of cells that are evidently in the first maturation 

 division, but with the chromosomes so massed together that no 

 exact determination of their number could be made; a still more 

 proximal zone of smaller cells in mitosis probably represents the 

 second maturation division, and toward the center enlarging sper- 

 matids in groups of four are recognizable. In the central space 

 many spermatids and a few evidently nearly mature spermatozoa 

 are present.^ The vas deferens is lined by slender columnar 

 cells, surrounded by a thin layer of connective tissue and muscle 

 fibers. The tubes of the seminal vesicles are Uned with an epi- 

 thehum of tall slender cells with clear basal nuclei and prominent 

 nucleoli. These cells are evidently glandular, for dark secretion 

 granules occur in the cytoplasm and a fluid secretion, staining 

 yellow with iron haematoxylin and orange G, is found in the lumen. 

 Muscle fibers and connective tissue form the outer part of the 

 walls of the seminal vesicles, and no spermatozoa have been 

 observed within the vesicles. 



The fat-body in the mature first-form nymph forms a nearly 

 solid mass between the viscera and the body wall, completely 

 enveloping the sex organs. 



^ Stevens ('05) has made a brief study of the spermatogenesis of Termopsis 

 angusticollis, presumably of the first form. She states that the spermatogonia! 

 number of chromosomes is twenty-six, and that there is one unique feature in the 

 development, namely, that there is only a nuclear division and no division of 

 the cell body of the first and second spermatocytes, so that the four spermatids 

 resulting from a primary spermatocyte actually develop as four nuclei within a 

 single cell body, and appear throughout development in groups of fours. 



