ATYPICAL MITOSIS AND OTHER NUCLEAR PHENOMENA 195 



near the nucleus during the growth period. When special methods for 

 the study of chondriosomes and Golgi material developed, however, it 

 became apparent that chondriosomes, chromidia, secretion droplets, 

 and other ergastic bodies had been hopelessly confused and that many of 

 the elements which had passed as chromidia were, in reality, chondrio- 

 somes and other materials for which there was no evidence of nuclear 

 origin. ^^ Cowdry points out that " ... in practice, under the heading 

 of chromidia, we have therefore to deal with a variety of substances 

 which have been hastily grouped together on account of their general 

 affinity for 'basic' stains and their supposed relation to nuclear chromatin 

 and for which no special methods of fixation are required. It is a branch 

 of cytology which has developed almost wholly apart from methods for the 

 study of living cells." 



At present it seems best to reserve the term "chromidia" for the 

 scattered chromatic matter in Protista with no formed nuclei, and in 

 other organisms for the small bodies in the cytoplasm which resemble 

 nuclear matter in composition and chromaticity more closely than do 

 the chondriosomes and other ergastic substances. The view that chro- 

 matic granules are transferred bodily through the nuclear membrane has 

 not been well substantiated, but that a nucleic acid compound passes the 

 membrane in solution, takes the form of granular "chromidia" as it 

 reaches the cytoplasm, and is transformed into strands and clumps on 

 fixation is probable (van Herwerden). Such manifestations of nucleo- 

 cytoplasmic interchange have been clearly shown in echinoderm eggs," 

 although their full significance and their relation to the general problem 

 of chromidia are not yet apparent. ^^ 



36Duesberg (1911), Faure-Fremiet (1910), Hirschler (1913), Nussbaum (1913), 

 Jorgensen (1913c), E. V. Cowdry (1924a). The chromidia of Adinosphcerium are 

 ergastic, according to Rumjantzew and Wermel (1925). 



^ Danchakoff (1916), Tennent (1920). 



^ See further on the subject of chromidia Kofoid (1921), Agar (1920a), E. V. Cow- 

 dry (1924a), and Wilson (1925, p. 700). 



