505 



stage of the former which shows the three bodies in question. In this 

 particular instance the two smaller bodies were united by a linin-like 

 thread but this is not always true. Even in the earliest contraction 

 phase when the nuclear filaments are concentrated into a dense tangle 

 at one side of the nucleus, if the preparation has been strongly deco- 

 lorized, one may see these two or three bodies shining out intensely 

 black through the grayer mass of the tangled fibres (Fig. 3). The 

 larger comma-shaped body is conspicuously visible. A short distance 

 to the left lies another deeply stained chromatic mass which one is 

 at a loss to know whether to regard as an elongated single body or 

 as two closely approximated smaller bodies. In this particular pre- 

 paration, yet another body was to be seen at the opposite side of the 

 nucleus. It is a question as to whether this should be considered as 

 one member of the usual small pair or as a distinct additional body. 

 The latter alternative is not an improbable one because occasionally 

 additional small chromatic bodies were present although never so con- 

 stant in number or appearance as the three which have just been 

 described. 



Concerning the regular pair, of small chromosomes or chromatin 

 nucleoli little further could be determined. At the time of division 

 of the primary spermatocyte one chromosome considerably smaller 

 than the others is to be seen, but no evidence was discovered to 

 point to these two chromatin nucleoli as its precursors any more than 

 to any other two of the several small ones which belonged to the 

 spermatogonial set. In a very few cases in the late prophase of the 

 primary spermatocyte division, a pair of small chromosomes, apparently 

 not yet conjugated, were to be observed connected by a barrel-shaped 

 mass of dense material staining deeply with the cytoplasmic stain. 



These circumstances together with the fact that occasionally a 

 precocious division of the small chromosome may be observed (Figs. 11, 

 12) cause one to suspect that we may be dealing with two chromo- 

 somes comparable to the m-chromosomes of Wilson^) and other 

 investigators of maturation phenomena in the Tracheata. I cannot 

 affirm, however, that in the guinea we are dealing each time with the 

 same pair of small chromosomes because there are several small ones 

 to be seen in the spermatogonia and either on account of individual 

 variations in size or because of the inconstant action of reagents there 

 is too great a fluctuation in size to judge of their respective identities. 



1) E. B. Wilson, Studies on chromosomes. Journ. of Exp. Zool., 

 1905, 1906, 1907, 1908. 



