242 MICHAEL F. GUYER. 



In my earlier paper ('09^), based upon a much more meager 

 series of preparations and on the whole considerably less satis- 

 factory from the standpoint of technique, I made mention of a 

 third chromosome which was at times associated with the curved 

 one. A more extensive survey of material shows this to be of 

 much less frequent occurrence than I then thought it to be, and 

 probably of no special significance. Such a smaller chromosome 

 may infrequently be seen either toward one pole along with 

 the X-like body or alone, or even toward the opposite pole. So 

 far as I can analyze the condition it is merely one division product 

 of one of the smaller chromosomes of the equatorial plate which, 

 following a precocious division, has passed on in advance of the 

 other chromosomes toward one pole. My earlier drawings also 

 give the impression of considerable irregularity in the outline 

 of the chromosome there designated as the odd. While such 

 irregularities may be found I must conclude from my later 

 material that the appearance is due in the main to unsatisfactory 

 fixation as my recent, better preparations all show what, when 

 one considers the difficulty of the material to be handled, is a 

 surprising uniformity in the appearance of this body. Photo 8 

 illustrates what may be regarded as the type. Indeed, in my 

 study of this element, as I came to examine by the hundreds 

 division figure after division figure it became impressed upon 

 me that this was in reality the one most constant identifiable 

 element in the whole phase of spermatogenesis. 



If this X-like body is merely accidental, then it is one of the 

 most astonishingly consistent accidents I have ever encountered. 

 It has a relatively constant size and shape, it ordinarily is not 

 likely to be confused in the least with other elements present in 

 the spermatocyte, and it is an accident which has the very same 

 appearance in the testicular cells of Langshan, Plymouth Rock 

 and Rhode Island Red fowls. Furthermore, a similar accident 

 occurs in the guinea-fowl, only there it is consistently comma- 

 shaped (Fig. 1 60) instead of being a curved element of uniform 

 thickness. Moreover, in the guinea-chicken hybrid a similar 

 element resembling more that of the guinea parent can be 

 identified, and lastly, on the accident theory, the crowning 

 wonder is that in all of these forms, the element in question 



