WENRICH: SPERMATOGENESIS OF PHRYNOTETTIX MAGNUus. III 
Miss Nowlin (’08) describes for Melanoplus bivittatus a precocious 
tetrad (no. 11), which always appears in the metaphase as a rod 
extended parallel to the spindle-axis. Such is.also the behavior and 
form of chromosome A. Furthermore, I have examined slides of 
Melanoplus material and find that it also has a spireme loop that stains 
more deeply than the others. May not this precocious tetrad of 
Melanoplus be related to chromosome A of Phrynotettix? 
Early in the course of my investigation I had the opportunity of 
looking over some of Dr. McClung’s collection of slides of acridian 
material, and, though a thorough study was not made, I could easily 
recognize in the pachytene stage of a number of species a spireme loop 
which stained more deeply than the others. Such loops were found, 
for example, in species of Aeoloplus, Amphitornis, Arphia, Brachy- 
stola, Hadrotettix, Hesperotettix, Hippiscus, Melanoplus, Phaetaliotes, 
and Stenobothrus. One characteristic of such threads, which, how- 
ever, is not so marked in Phrynotettix, is a tendency to become asso- 
ciated with the accessory chromosome. This is particularly true of 
Melanoplus and Stenobothrus, the forms in which Davis (’08) was led 
by this close association to describe a “double monosome.” There 
can be no question, I think, that these “double monosomes”’ were 
merely the accessory chromosome plus one of these deeply stained 
spireme segments. In view of these facts, the suggestion offers itself, 
that similarity in the properties and behavior of certain chromosomes 
in different species may be correlated with their taxonomic relation- 
ships. Such correlation was, indeed, seen and discussed some time 
ago by McClung (’082). Meek (’12) has already made a comparative 
study of the sizes of the chromosomes in several species of Steno- 
bothrus, and has reached the conclusion that the five smaller pairs 
of chromosomes are of the same size in all species, but that the large 
(V-shaped) pairs differ from one species to another. It still remains 
to be seen whether or not the chromosomes of different species can be 
compared on the basis of their details of organization and behavior, 
as well as size. 
2. The heterochromosomes.—I believe most observers agree that 
the heterochromosomes maintain their individuality through the 
growth-stages of the male germ-cell cycle. On another page (p. 87) 
I have called attention to the similarity in behavior between the 
autosomes and the accessory, this has also been noted by many others, 
so that there is no very good ground for setting up a claim to funda- 
mental distinction between the two kinds. It seems to me, therefore, 
that if we admit a persistent individuality for the heterochromosomes, 
