WENRICH: spermatogenesis of PHRYNOTETTIX MAGNUS. 115 



Pinney reached a similar conclusion. Davis, on the other hand, 

 could recognize only an irregular outline for the nucleus, and did not 

 identify the vesicle of even the monosome with certainty. Gerard 

 ('09) saw the hyaline regions about the telophase chromosomes of 

 Stenobothrus, and stated that the nuclear membrane was formed in 

 connection with them. Since similar conditions have been reported 

 by so many observers, it would seem that these vesicular structures 

 are the result of normal processes and not, as claimed by Vejdovsky 

 ('11-12), artifacts. 



If we turn to accounts other than those on orthopteran spermato- 

 genesis, we find that the formation of chromosornic vesicles out of 

 individual chromosomes in the telophase is by no means of rare 

 occurrence. Van Beneden ('83) noted in his work on Ascaris that 

 each of the two chromosomes of the female pronucleus often formed 

 a separate 'half -nucleus.' Hacker ('95b) observed that the chromo- 

 somes of the early cleavages of Cyclops brevicornis formed two groups 

 of "Blaschen," one group from the maternal and another from the 

 paternal pronuclei. Conklin ('02) calls attention to the occurrence 

 of such chromosomic vesicles, and gives the history of the nuclear 

 changes during the cycle of division in Crepidula as follows (p. 45) : — 

 "(1) The cliromosomes, consisting of chromatin enclosed in a linin 

 sheath, divide and move to the poles of the spindle, where they par- 

 tially surround the spheres. (2) Here they become vesicular, the 

 interior of the vesicle becoming achromatic, though frequently con- 

 taining a nucleolus-like body, while the wall remains chromatic. (3) 

 These vesicles continue to enlarge and then unite into the "resting 

 nucleus." The nuclear membrane is composed of the outermost walls 

 of the vesicles, while the inner walls stretch through the nucleus as 

 achromatic partitions. The chromosomal vesicles for the egg and 

 sperm nuclei remain distinct longer than those from the same nucleus 

 .... Such vesicles are found generally, if not universally, in the early 

 division of ova, though they are not usually found in other mitoses." 

 Small wood ('05) describes similar chromosomic vesicles in the eggs of 

 nudibranchs. He found that during the "rest-pause" between the 

 first and second maturation divisions the chromosomes frequently 

 have distinct vesicles. There may be a single vesicle for all the 

 chromosomes, or a single vesicle for each chromosome; all conditions 

 between these two extremes occur. Medes ('05) in her work on 

 Scutigera found in the second spermatocytes (p. 174) that: — "There 

 is no immediate formation of a nuclear membrane, but each separate 

 chromosome, as it disintegrates, becomes enclosed in a membrane of its 



