CHROMOSOME STUDIES 267 



Again the one- V- type individual of Jamaicana has an impor- 

 tant bearing on the subject of individual continuity. Here in 

 the same animal one member of each of the pairs 14 and 16 

 exists as a separate rod in every cell, while the mates of these exist 

 in the same cells linked together. Whether the chromosome 

 in the ancestral species was a V or two rods, I cannot say. If 

 the ancestral chromosome was a V, then a break has occurred 

 at some time and this break has been handed down generation 

 after generation. On the other hand if a fusion has occurred 

 at some time, then the fusion condition has been handed down. 

 Whichever hypothesis we adopt, this much seems certain, that 

 the thread in the case of the V retains its identity from cell to 

 cell and likewise in the case of the rods. If we argue for a fu- 

 sion of the rods to form the single V at each prophase, how can 

 there exist in the same cell homologous rods which do not form 

 V's? This to me is an argument against the 'manouvre hy- 

 pothesis' of Fick, viz., that chromosomes represent tactical 

 formations produced anew in the cell, and the somewhat simi- 

 lar hypotheses advanced by Meves, Gigho-Tos and Granata. 



It seems to me that further strong arguments in favor of 

 the individual continuity of the chromosome thread are the 

 deficient no. 4 of Tettigidea (figs. 104, 110, 115, 119, 120, 122 

 and Study III) and the no. I's of Acridium (figs. 136-147, and 

 Study III). Here we have in these animals every cell in the 

 body, both germ and somatic, showing in the one case the de- 

 fective no. 4 chromosome, in the other case the abnormally long 

 no. 1. That these chromosomes were probably present at the 

 fertilization of the egg, is shown in the first case by their presence 

 in every cell of the body and in the second case by their being 

 distributed as units to half the second spermatocytes. This is 

 also reinforced by the fact that the same abnormal long chromo- 

 some has in all probability been found in both male and female 

 animals. That these chromosomes are abnormal, I think no 

 one who reads the description of them will doubt. Now, in 

 the case of the defective no. 4, all cells in division showed it 

 to be of constant relative size. The same may be said of the 

 long no. 1 of Acridium; not only is it true for all cells of one 



