m'clung: spermatocyte divisions op the locustid.k. 201 



that it was primarily designed to indicate the fusion of the 

 spermatogonial chromosome to produce the chromosomes of the 

 spermatocyte. He states this clearly in the following words : 

 "Moore (1895) first gave the name 'synaptic phase' to that 

 stage in the growth period of Elasmobranchs when the reduc- 

 tion in the number of chromosomes takes place. Accordingly, 

 the criterion of the synapsis stage is, first of all, the combina- 

 tion of univalent chromosomes to form bivalent ones ; whether 

 the chromosomes are then densely grouped or not is of second- 

 ary importance." 



(b) The Spermatocytes of the Locustidee and Acrididte. 



The formation of the first spermatocyte chromosome gives 

 us an insight into the later changes undergone by these ele- 

 ments such as cannot be obtained in any other way. The great 

 importance attaching to this part of the spermatogonial process 

 renders it desirable to exhaust every effort in obtaining a knowl- 

 edge of the actual changes here taking place. This thought 

 has been held constantly in mind during the progress of these 

 investigations, and every point of resemblance or of difference 

 between the various species studied has received careful atten- 

 tion. Despite variations in details, however, I must state that 

 the essential features of the maturation divisions are the same 

 in all species of the Orthoptera examined. It is true that as 

 yet only two families, the Acrididre and the Locustidte, have 

 been worked out in a detailed way, but the close agreement be- 

 tween these raises a strong presumption in favor of the general 

 prevalence of the type. The processes of the two families have 

 already been described in detail, but it will perhaps be well to 

 call particular attention to some points worthy of mention. 



The general appearance of the material derived from the two 

 families is quite different in sections. Even the hastiest obser- 

 vation will show this. The spermatocytes of the Locustid testis 

 are much smaller, denser and more deeply staining than those 

 of the AcrididiBe. The relative quantity of chromatin is greater, 

 so that it is possible by microscopical examination of a section 

 to tell whether it was prepared from Locustid or Acrididan ma- 

 terial. 



The transformation from the telophase of the last spermato- 

 gonial division to the prophase of the first spermatocyte is 

 marked by practically the same changes in both families. It 



