C. E. MCCLUNG. 



sary to look for modifications in size and proportions of parts. 

 In drawings made at a magnification of 2,875 diameters it is 

 found that the accessory chromosome of H. spcciosns in meta- 

 phase measures on an average about 12 mm. while in H. viridis(?) 

 it is near 1 1 mm. This difference is only slight, but if the chro- 

 mosomes associated with the accessory are 

 measured it will be found that the variation 

 in size is considerable. Thus in H. speciosns 

 the average length is in the neighborhood of 

 20 mm. while in H. viruiis it is not over 15 

 mm. Here is a very pronounced specific 

 variation which is probably accompanied by 

 corresponding variations in the other chro- 

 mosomes. Along with this difference in size 

 of the chromosomes there goes a corre- 

 sponding variation in the achromatic figure. 

 The spindle in the first spermatocyte of //. 

 spcciosns is long and slender, while in H. 

 I'iridis (?) it is short and heavy. There are 

 probably many other less obvious differences 

 which I have not discovered in this preliminary survey. I hope 

 in time to present these in detail. 



3. Tlic Chromosomes of Mermiria sp. 



In the spermatogonia of Mermiria there is again found the 

 heterotypical mitosis of chromosomes. The early synapsis of 

 chromosomes, which is the occasion for the unusual form of 

 mitosis, is encountered very frequently in spermatogonia, and I 

 shall have occasion to refer later to instances in certain species 

 where it is very marked. In the prophase of the first sperma- 

 tocyte of Mermiria, there is again found a multiple chromosome 

 which shows the same constitution as the one in Hesperotettix. 

 The pronounced difference between the smooth homogeneous 

 accessory chromosome and the rough granular elements of the 

 the tetrad joined to it is strikingly shown in the beautifully clear 

 nuclei of this Tryxaline. So far the case is parallel to that ex- 

 hibited by Hesperotettix, but just before the metaphase a singular 

 and entirely unique association of the hexad multiple chromosome 



FIG. 9. A similar 

 cell in anaphase. The 

 disproportion between 

 the accessory part of the 

 dyad and the other 

 member is well ex- 

 hibited. 



