THE FUNDAMENTAL ORGANIZATION 55 



that an effort has been made to discriminate between the various 

 granules in the Protozoa which stain intensely with the basic 

 stains, and to distinguish the chromatin granules which enter into the 

 make up of chromosomes from other chromatoid granules which are 

 distributed throughout the cell, particularly the chromidia and the 

 volutin grains. This is the more difficult in Protozoa because 

 chromatin granules are not necessarily confined to the nucleus. 

 Even in Metazoa and plants there are times during division when 

 the chromatin is not confined within a nuclear membrane. In 

 the Protozoa such a condition is permanent in many cases (e. g., 

 in some flagellates; in Dileptus gigas, Holosticha, etc.). In other 

 cases the nuclear chromatin, by transfusion or by nuclear fragmen- 

 tation, spreads more or less widely throughout the cell protoplasm 

 (rhizopods, Actinosphaerium eichhornii, etc.). Here in different 

 species, the fate of the distributed chromatin varies. In some 

 cases this diffusion of chromatin indicates a degenerative change, 

 the chromatin ultimately losing its characteristic reactions. Thus 

 in Actinosphaerium eichhornii, Hertwig has shown that, under 

 adverse conditions such as starvation, or overfeeding, or during 

 periods of depression, such distribution of the nuclear chromatin 

 occurs, the granules ultimately becoming transformed into a 

 characteristic pigment of the cell. In other cases the distributed 

 granules retain their chromatin nature and according to numerous 

 observers are ultimately aggregated into minute secondary nuclei 

 which become the nuclei of conjugating gametes (see p. 69). In 

 these instances, other chromatin which is retained in the "primary 

 nucleus" takes no part in the germinal activities but degenerates 

 and disappears after the gametes are liberated. It must not be 

 inferred that germinal chromatin is thus distributed in the cyto- 

 plasm in all cases; on the contrary in the majority of Protozoa the 

 gamete nuclei are derived by division of the morphological nucleus 

 with its contained chromatin, and some authorities, notably Kofoid 

 (1921) deny in toto the origin of gamete nuclei from chromidia. 



While chromatin thus has a definite germinal function there is 

 equally little doubt of the important participation of the nucleus 

 and presumably of chromatin in the ordinary metabolic activities 

 of the cell. Thus, if an Amoeba proteus or the ciliate Uronychia 

 transfuga (see Fig. 135, p. 262), be cut into two portions one of 

 which contains the nucleus while the other is enucleate, the former 

 portion only will digest and assimilate food, grow and regenerate 

 the lost part, while the enucleate portion will continue to move 

 and manifest various activities characteristic of destructive metab- 

 olism, but it will not take in food, nor digest what food may have 

 been taken in before cutting, and in the course of a week or ten 

 days it dies (Hofer, Verworn, Balbiani and many others). 



It is evident that chromatin is directly associated with all of 



