M'CLUNG : SPERMATOCYTE DIVISIONS OP THE LOCUSTID.K. 213" 



longitudinale; nous regardons comme un point capital dans notre travail d'en 

 mettre l'existence hors de doute et pour cela nous desirous ne faire appel qu'a 

 des images extremernent claires. Nous conside'rons comme telles les fig. 129 et 

 130 rapprochees l'une de l'autre. 



"II est de toute Evidence que le chromosome a, fig. 130, n'est que le chro- 

 mosome de meme designation, fig. 129, dont les deux anses jumelles se sont 

 clivres. De meme, le chromosome en forme de boucle, c, fig. 129, dont les 

 deux branches representent, comme nous l'avons fait remarquer, deux anses 

 jumelles, se retrouve avec un clivage tres Evident en d, fig. 123. On pourrait 

 faire les memes rapprochements entre b, fig. 105, et a, fig. 107; ici, le clivage 

 est moins avanc£, mais les granules sont nettement divisCs." 



I am obliged to confess that I have never seen in other spe- 

 cies of this genus any appearances that would incline me to 

 place an interpretation upon them such as does our author upon 

 these. I would venture to suggest, on the contrary, that the 

 chromosomes represented in figure 129 have not as yet demon- 

 strated any division, but show merely irregular spaces between 

 chromosomes. At even an earlier stage (figs. 5, 37, and 38), 

 I have shown the formation of the tetrads by means of simul- 

 taneous cross and longitudinal divisions so clearly that pre- 

 sumed successive divisions, as represented by de Sinety, cannot 

 be regarded as occurring. 



Finally, I would emphasize the fact mentioned in connection 

 with the discussion of the cross-shaped chromosomes, that 

 where the elements of one of these compound chromosomes in- 

 tersect they lie in one plane, and are not superimposed vpon each 

 other, as de Sinety's theory demands and as his figures represent. 

 This was shown clearly in Paulmier's figures as well as in my 

 own, and is even more clearly demonstrated, if posssible, in 

 the very long, slender chromosomes of the myriapods, which I 

 have observed in Mr. Blackman's preparations. This, and the 

 continuity of the chromatin in contiguous arms of the cross, is 

 alone sufficient to disprove de Sinety's theory, and, fortunately, 

 is easily demonstrated. This same fault of de Sinety's is en- 

 countered, in another form, in his discussion of the ring figures. 

 He asserts that the halves of the rings are pulled past each 

 other while they lie in the plane of the spindle axis. Herein 

 my observations fail entirely to agree with his. The rings lie 

 in the plane of the equator, and no elements of the mitotic 

 figure show a lateral displacement of the separating halves 

 equal to the width of the chromosome when viewed in this 

 plane. 



