WENRICH: spermatogenesis of PHRYNOTETTIX MAGNUS. 117 



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. Gregoire ('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 chromor 

 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 ('13) also finds continuity of the chromosomes 

 in plants through the " rest-stage." He beheves 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 cliromosome. This spiral thread becomes the prophase 

 chromosome of the succeeding division. He introduces the term 

 "spirophase" to designate the so-called "rest-stage." 



