26 J. BRONTE GATBNBY 



the developing Miastor egg (32). Just before his untimely- 

 death Professor L. Doncaster was examining this problem, 

 and sent me some oi his slides for examination and sugges- 

 tions ; all that I could do was to recommend the use of stains 

 such as Auerbach and Pappenheim, and methyl blue eosin. 

 Digestion tests and such other microchemical tests are im- 

 possibk! when one is working on the minute spindle in a very 

 small C!gg. It certainly seemed to me that in the slides sent 

 by Professor Doncaster the intermediate bodies were derived 

 from the ends of the chromosomes as in Miastor. ^ Here again, 

 however, we are faced with the same difficulty with regard 

 to staining test, as I have pointed out with reference to the 

 nucleolus: we are not justified in saying that a substance is 

 chromatin simply because it selects methyl green from the 

 Pappenheim or Auerbach stains ; no one would care to say 

 that the head of the spermatid was not chromatin, yet at 

 certain periods it will select the red stain from the Pappenheim 

 or Auerbach fluid. To my mind it is useless to declare that 

 the head of the sperm at such stages is not true chromatin, 

 but has only changed its chemical nature ; the head of the sperm 

 is derived from chromosomes before it reaches the egg and 

 breaks up into chromosomes when it has penetrated into the 

 egg. The spermatid nucleus takes the red stain from the 

 Pappenheim or Auerbach fluid possibly because the arrange- 

 ment of its surface or internal substance is more favom-able 

 to the molecules of the red stain, and unsuited for the absorp- 

 tion of the green stain. 



The facts of the matter are that we know very Httle about 

 the relationship between the nucleolus and the chromosomes, 

 both during mitosis and during interkinesis ; the same remark 

 applies when we come to the subject of the microchemical 

 nature of the nucleolus. I believe that a good step towards 

 the elucidation of the first-mentioned problem has been taken 

 by H. M. Carleton. 



This observer has shown that the nucleolus of certain 



vertebrates contains an argentophil core, or is related more 



' I have often wondered why this work of Prof. Doncaster was not 

 edited and publiyhed. 



