WENRICH: SPERMATOGENESIS OF PHRYNOTETTIX MAGNUS. 7 
coiled chromatic portion will become its chromonema. In successive 
generations, therefore, there is a changing composition of the chromo- 
somes. During each katachromasis, the ground substance of the 
chromosome dissolves, leaving the chromonema, which becomes 
differentiated into the two kinds of substance found in the chromo- 
some of the next generation. This is an ingenious theory, to say the 
least, and carries with it some measure of support for the theory of 
individuality, inasmuch as each new chromosome is formed out of the 
substance of a preceding one. 
I have found nothing in my studies to support any one of these 
theories to the exclusion of the others. It is rather surprising, how- 
ever, that Vejdovsky found no indication of the chromosomic vesicles 
in the spermatogonia of the Orthoptera that he studied and that he 
regards those seen by others as artifacts. I find little evidence of a 
chromonema in the telophase of the spermatogonia, and what evidence 
there is would indicate that the chromatin becomes distributed on the 
inner surface of the vesicular walls, not on the outer surface of an 
achromatic core. In the telophase of the last spermatogonia, I find 
a spiral thread forming, but it develops out of the chromatin at the 
middle of the area occupied by a vesicle. But whether we accept 
any one of these theories, or reject all of them, there still remain the 
strongest grounds for believing, as they all indicate, that there is 
some underlying organization which is in some way perpetuated 
for each individual chromosome. I am inclined to the belief that 
this organization involves both chromatic and achromatic substance. 
In plant material evidence which indicates a continuity of the 
chromosomes has not been wanting. Grégoire (’07, ’10) believes 
that the results of his own investigations and those of others on plants 
furnish strong support for the individuality theory. Stout (’12) has 
recently added evidence for this belief in his work on Carex aquatilis. 
He says ('12, p. 36): — “The chromosomes are present in all resting 
nuclei as visible units of a definite number. These individual chromo- 
somes can be traced as such through all stages of both somatic and 
germ-cell divisions, with the exception of the various stages of synapsis 
(synizesis).”” Lee (’18) also finds continuity of the chromosomes 
in plants through the “rest-stage.”” He believes that the chromosomes 
of even the metaphase become vacuolated, that this vacuolization 
increases in the telophase, where, later, a spiral thread is formed out 
of each chromosome. This spiral thread becomes the prophase 
chromosome of the succeeding division. He introduces the term 
“spirophase” to designate the so-called “rest-stage.” 
