40 GEORGE T. HARGITT 



of no significance where it occurs. Jorgensen finds chromatin 

 stains and mitochondrial stains and technique to be very uncer- 

 tain, and neither of these, or any other staining method, is to 

 be depended on, since they do not differentiate bodies of diverse 

 origin and chemical composition. 



An even stronger criticism of our staining methods and all 

 microchemical tests is made by van Herwerden ('13). Our 

 technique, she holds, is so primitive as to be useless in the identi- 

 fication of chromatin; evidence from stained, fixed preparations 

 is not valid; action of weak or strong alkalis or acids does not 

 give satisfactory results; digestion by pepsin and trypsin leads 

 to no intelligible information; none of the usual tests are of any 

 great service. This author uses nuclease as an enzyme in 

 digestion experiments to test for chromatin (nucleic acid content) 

 in the basic cytoplasmic granules of echinoderm eggs. Using 

 ripe eggs, very simple experiments demonstrated the basophile 

 granules of the cytoplasm to ''consist of a nucleic acid com- 

 pound." In younger oocytes, where chromidia had been de- 

 scribed against the nuclear membrane, the nuclease experiments 

 show the presence of nucleic acid compounds. Van Herwerden 

 is somewhat doubtful as to the origin of these chromatin particles 

 and hesitates to interpret it as a migration of chromatin from the 

 nucleus. However, by observing living oocytes of Sphaerechinus, 

 she could follow a movement of refractile granules to the nuclear 

 membrane where they disappeared, and at the same time granules 

 appeared in the cytoplasm close to the nuclear wall. Van Her- 

 werden concludes that there is a possibility of the diffusion of 

 nucleic acid compounds from the nucleus into the cytoplasm, 

 but no direct proof of this. I suppose, in the very nature of the 

 process, one could not expect to secure absolute proof of this 

 passage, but van Herwerden seems to have obtained evidence 

 which renders such diffusion highly probable. In all experi- 

 ments with nuclease, the chromatin of the nucleus was affected 

 in the same way (though to a much less degree) as the basophile 

 granules of the cj^toplasm. From the experiments and observa- 

 tions of van Herwerden there would appear to be ample warrant 

 for the belief that nuclear material passes from the nucleus into 



