580 FERNANDUS PAYNE 



somes is so irregular that I cannot say whether this rule is fol- 

 lowed. Lagging chromosomes are seen in both divisions. In the 

 first they may or may not divide. In the second they become 

 very much elongated and while I have not seen them dividing, 

 Zweiger ('06) and Stevens ('10) described lagging chromosomes 

 in the second division which do divide. In some cases these 

 lagging chromosomes become so drawn out that it seems doubt- 

 ful whether they ever reach either pole of the spindle. Perhaps 

 a failure to conjugate in synapsis is understandable, but the 

 reason for the irregular behavior of the single chromosomes is 

 not so clear. The only case approaching these irregularities 

 is found ia the supernumerary chromosomes of Metapodius and 

 Diabrotica, but here such chromosomes are supposed to be 

 functionless and on the road to degeneration. 



I do not wish to draw any conclusions from the above obser- 

 vations, as the amount of material studied is too small. It might 

 be well, however, to point out the principal questions which need 

 further study. First, do the spermatids which receive 11, 12, 13 

 and 14 chromosomes become functional spermatozoa? Secondly, 

 if so, do we find variations in the spermatogonial and oogonial 

 number among different individuals of the species? Thirdly, 

 if the spermatogonial and oogonial number is kept constant, 

 what is the means of regulation? One other important problem 

 which may be solvable in this material deserves mention. For 

 some time it has been a disputed question whether the longi- 

 tudinal split which appears in the chromatin thread following 

 synapsis, is due to separation of maternal and paternal elements 

 which have previously conjugated side by side, or whether it is 

 a longitudinal splitting of chromosomes which have united end 

 to end. In Forficula some of the chromosomes remain single 

 and, so far as I have been able to make out, behave during the 

 growth period as the bivalent autosomes. It seems to me that 

 it may be possible to distinguish these single chromosomes from 

 the double ones, at least in the early prophases of the first divi- 

 sion, and if so, a comparison between the presence or absence 

 of a longitudinal split in these sirgle chromosomes with the same 

 in the double chromosomes, would prove of interest and perhaps 

 give us some light on the question of synapsis. 



