SPEEMATOGENEBIS OF STENOBOTHRUS VIRIDULITS. 9 



contact with the connective-tissue cells. Gerard further distinguished it in 

 Stenohotlirus higuttulus' by its deeper cytoplasmic colouring ; but I have not 

 found this in my material. The cluster of primary spermatogonia is 

 surrounded by numerous connective-tissue cells, recognizable by their small 

 size and deeply stained nuclei. The secondary spermatogonial groups are 

 completely enclosed by cyst-walls, formed from connective-tissue cells, and 

 lie posteriorly to the primary spermatogonia in irregularly disposed clusters, 

 often so closely packed that the cells become distorted. Bach group has 

 been formed by repeated division of a single cell, originally extruded from the 

 primary spermatogonial figure, so that there is a continuous stream of cells 

 passing towards the posterior end of the follicle. A secondary spermatogonial 

 cyst is shown on Plate 1. fig. 2, from which it will be seen that these cells 

 closely resemble the primary spermatogonia, but are easily distinguishable 

 by the absence of the apical cell. 



As in the case of the primary spermatogonia, the resting-stage nucleus 

 shows a series of chromatin granules disposed along linin threads : I have 

 been unable to discover whether we are dealing here with one continuous 

 thread, much convoluted, or with a number of threads, irregularly placed 

 ill such a manner that they combine to give this reticular appearance. 

 Montgomery seems to have experienced the same doubt in the case of 

 /Syrhula. Davis merely describes a network, in which chromatin granules 

 are massed at the intersections of the linin threads. 



There are two spermatogonial generations ; and this agrees with the 

 results of Montgomery upon Syrhula acuticornis, Gerard upon Stenohothriis 

 higuttulus, and Davis upon numerous members of the Acrididse and 

 Locustidse. Sutton however has declared that there are eight in Bracliy- 

 stola ; and Wilcox has been unable to determine the exact number in 

 Caloptenus femur-mhrum. McClung suggests that the number varies with 

 the species. 



In the resting-stages the nucleus is not deeply stained. The prophase of 

 ; division is characterized by the flowing together of granules on the linin 

 ■■ threads ; and these chromatin particles become more and more closely 

 associated until they form the ragged filaments, representing the forerunners 

 of the compact bodies that later appear on the periphery of the karyokinetic 

 spindle. As condensation proceeds, the chromatin exhibits greater affinity 

 for the iron haematoxylin, so that distinct correlation exists between the 

 intensity of staining and the degree of proximity of the associating particles. 

 The formation of the spindle is preceded by the appearance of two small 

 asters in the cytoplasm, close to the periphery of the nucleus. The chromatin 

 filaments have by this time assumed the shapes and sizes characteristic of 

 the qhromosomes ; and they now arrange themselves on the equatorial plate, 

 preparatory to division, the metaphase complex showing seventeen chromosomes 

 of varying shapes and sizes. 



