504 D. H. WENRICH 



reduction occurred in them, and then by analogy, probably 

 occurred in all the others. Gerard ('09), though somewhat un- 

 certain, likewise concludes that the plane of separation of the 

 atelomitic rings is along the primary plane and is therefore re- 

 ductional and then says (p. 579) : ''Personne ne contestera cepen- 

 dant que tous les chromosomes doivent se comporter a ce point 

 de vue de la meme fagon et que Ton est autorise a appliquer, a 

 tous, ce que Ton a vu d'une fagon irrefutable chez quelques uns 

 d'entre eux." I think there is danger in drawing such analogies. 



Meek ('11) says he is not able to. discover whether reduction 

 occurs at the first maturation division or the next but thinks 

 possibly both divisions are equational and a numerical reduction 

 takes place only as a result of lateral association of chromatin 

 granules or masses on the reticulum of the threads prior to the 

 primary spermatocyte prophase. Meek thus failed to see the 

 parallel conjugation (though he assumes it may occur) and 

 does not recognize the primary longitudinal split (along which 

 one division takes place) as the space between conjugants. 



McClung ('14) mentions the difficulty in determining the plane 

 of division in the first spermatocyte and says, p. 665-666: "It 

 is probably true that until the relations of the chromosomes 

 during the synaptic phase are definitely determined it will not 

 be possible to assert unequivocally that the longitudinal axes 

 of the paired chromosomes of the first spermatocyte represents 

 the coincident axes of the spermatogonial chromosomes consti- 

 tuting it, for if there be a parasynapsis at any period there is a 

 possibility that the doubly split thread may open out along 

 the plane of the equational cleavage instead of along the. space, 

 between chromosomes. In either event the form of the re- 

 sulting chromosome would be the same." However he believes 

 that (p. 667) : "The sister halves of a chromosome remain closely 

 united here as in other generations of cells, and that separation 

 between parts of a tetrad is much more likely to occur along spaces 

 between whole chromosomes." If one were to apply the reason- 

 ing in the last sentence quoted to the cases under discussion one 

 would get variable results. Besides, I think I have sufficiently 

 demonstrated parasynapsis and therefore the existence of the 

 basis for the uncertainty mentioned. 



