THE FUNDAMENTAL ORGANIZATION 69 



characteristically with specific staining methods, thereby indi- 

 cating differences in their chemical composition. Amongst such 

 characteristic granular elements of the cytoplasm are (1) Chromidia, 

 found mainly in Sarcodina and Sporozoa; (2) Volutin grains, found 

 mainly in flagellates, but also present in Sarcodina and Sporozoa; 

 (3) Mitochondria, characteristic of all types; (4) Golgi apparatus, 

 probably universal; (5) Silver Line Si/stem of the Infusoria; (6) 

 Kinetic elements (for the latter see pages 88 and 104). 



1. Chromidia.— The nature and the functions of chromidia have 

 been and still are matters of controversy in which there are wide 

 differences of opinion. Hertwig (1879) early called attention to 

 extra-nuclear chromatin in Radiolaria and later (1899) described 

 the zone of cytoplasmic, deeply staining substance which extends 

 from one nucleus to the other and characterizes the dorsal region of 

 Arcella vulgaris and related forms. Hertwig called this the chrom- 

 idial net and homologized it w ith the extranuclear chromatin which 

 he had found in Radiolaria. At about the same time (1898, 1902) 

 Hertwig described the breakdown of nuclei and the distribution of 

 chromatin into the cytoplasm of Actinosphaerium eichhornii. To 

 such chromatin granules in the cytoplasm he gave the name "Chro- 

 midien" and their appearance was regarded as a sure indication of 

 the approaching death of the organism. 



These observations mark the commencement of a long controversy 

 over the question of chromidia duality which, so far as the Protozoa 

 are concerned, was first clearly announced by Schaudinn in connec- 

 tion with the life histories of the testate rhizopod Centropyxis 

 aculeata, the foraminiferon Polystomellina crispa, and some of the 

 endamoebidae. 



The chromidia! net of Centropyxis is similar to that of Arcella 

 and according to Schaudinn is the seat of the formation of second- 

 ary nuclei by origin de novo from the chromatin of the chromidial 

 net. These secondary nuclei become the nuclei of gametes while 

 the primary nucleus degenerates. Similarly in Polystomellina, al- 

 though there is no chromidial net, the cytoplasm of mature indi- 

 viduals of the asexual generation becomes filled with minute chro- 

 matin granules— chromidia which arise by fragmentation of the 

 primary nuclei and ultimately become the nuclei of gametes (Fig. 123, 

 p. 235). 



These findings by Schaudinn were subsequently confirmed by 

 Lister (1905) for Polystomellina crispa; by Elpatiewsky (1907) and 

 Swarczewsky (1908) for Arcella vulgaris; by Goldschmidt (1905) 

 for Mastigina and Mastigella belonging to the flagellate family 

 Rhizomastigidae; by Winter (1907) for Peneroplis pertusus, a fora- 

 miniferon; by Goette (1917) for Difflugia lobostoma. Similar obser- 

 vations were made in connection with Sporozoa of different kinds 

 by Leger and Duboscq for the gregarine Nina gracilis; by Swarc- 



