70 BIOLOGY OF THE PROTOZOA 



zewsky (1910) for a species of Lankesteria a hemosporidian ; by 

 Kuschakewitsch (1907) for Gregarina cuneata; by Lebedew (1909) 

 for the ciliate Trachelocerca phoenicopterus. The findings and con- 

 clusions of these different observers have been criticized by Doflein 

 (Lehrbuch, Fourth Edition), by Kofoid (1921) and by others, as 

 unconvincing and not, as yet, adequately confirmed, while the 

 suggestion is repeatedly made that the "secondary" nuclei arising 

 thus de novo from chromidia may be intracellular parasites. 



So far as the dualism of chromidia is concerned Schaudinn (1903) 

 was the first to suggest the idea by the term "somatochromidia" 

 for chromidia which are vegetative in function or the result, as in 

 Actinosphaerium, of degeneration, and by the term "gametochro- 

 midia" for chromidia which give rise to gamete nuclei. These 

 terms were turned into "trophochromidia" and "idiochromidia" 

 respectively by Mesnil (1905) with a slight difference in interpre- 

 tation of the former. Goldschmidt (1905) likewise indicated the 

 same interpretation by the terms "chromidia" and "sporetia" 

 respectively. 



Before accepting interpretations . as above, particularly in con- 

 nection with chromidia of the testate rhizopods, it is necessary to 

 determine whether or not the granules in question are really chro- 

 matin. Khainsky (1910) came to the conclusion that the chromidial 

 net of Arcella has an active part to play in nourishment of the 

 organism, and Zuelzer (1904) maintained that the chromidial net 

 of Difflugia is the seat of formation of a carbohydrate nutritive 

 substance of the nature of glycogen. If these suggestions prove to 

 be correct it would indicate a different chemical make-up for chro- 

 midia and intranuclear chromatin, and a difference which should 

 be detectable by microchemical tests. In this field, however, 

 observations are few and results are discordant. The chromidial 

 net of Arcella vulgaris stains black with iron hematoxylin, green 

 with the Borrel mixture and, usually, gives a negative reaction 

 with the usual Feulgen treatment. These results confirm Hart- 

 mann's experiment with pepsin under the action of which the 

 chromidial net of Arcella is dissolved out while the secondary 

 nuclei are conspicuous after subsequent staining. 



Belar (1926) and others apparently believe that Hartmann's 

 experiment gives a final answer in the negative to the question of 

 the chromatin nature of chromidia. This conclusion, however, is 

 somewhat premature for recent experiments with the Feulgen reac- 

 tion indicate that nucleic acid is certainly present at some stages. 

 With hydrolysis by strong hydrochloric acid at 60° F. followed 

 by the usual staining method the result is invariably negative, while 

 the primary nuclei show only a faint reaction. If, however, the 

 first part of the operation involving strong hydrolysis is omitted 

 and the Arcella material placed directly in the staining solution for 



