The Spermatogenesis of Hyijrid Peas 523 



that it is not seldom difficult surely to determine the character of 

 a given cell. To study the divisions from which the sporiferous 

 tissue arises it is necessary to obtain very young anthers indeed, 

 those which are merely slight protuberances on the primordium of 

 the flower. The difficulties in the way of studying the anther are 

 decidedly increased from the fact that the inflorescence consists of 

 not more than four or five flowers, all usually in widely different 

 stages of development. 



For the most part the nuclear division.s* in the sporogenous 

 cells of Fillbasket x Debarbieux are of the regular equational 

 type, quite the same as those in the somatic cells of the plant. 

 That is, fourteen segments are formed in the prophases and these 

 become arranged in the equatorial plate and in mctaphase are 

 already split before the migration to the poles of the spindle. In 

 anaphases the chromosomes are frequently L-shaped, although 

 not so sharply bent, and are arranged haphazard, that is, as purely 

 by chance. In the telophases the chromosomes unite end to end 

 and form a spireme ; this becomes changed into a delicate reticu- 

 lum in which all trace of the chromosomes as such disappears. 



In some of the later sporogenous divisions a departure from 

 the usual appearance was noted as in the case of the pure form 

 Fillbasket. In Fillbasket x Debarbieux the same curious associ- 

 ation of chromosomes two and two was observed in a few cases. 

 F. 6 shows an anaphase of the last sporogenous division ; the pair- 

 ing was even more clearly marked in the preparation than in the 

 sketch. The pairing was with a single exception observed in 

 anaphase or early telophase only. The exception is shown by 

 f. J, which is an equatorial plate in probably the last division be- 

 fore synapsis. I have not seen the association in early anaphase 

 for the reason perhaps that the chromosomes are at that time 

 under the influence of the spindle fibers. 



When the chromosomes reach the poles of the spindle they 

 unite by their polar ends, and these appear to fuse together, mak- 

 ing a more or less well-marked ring from which depend the chro- 

 mosomes in pairs. This is shown very imperfectly byy. 7, 8 and 

 p. In no case did I see a spireme which I could surely say was 

 continuous or which was made up of more than two elements ; 

 this may well be because the particular stage was wanting in the 



