n] GOLGI APPARATUS, CHROMIDIA 25 



tion of the Golgi apparatus hardly anything is known; 

 some further reference to it will be made later in connection 

 with the development of spermatozoa. 



Finally, a few words must be devoted to the so-called 

 chromidia observed in certain cells. It has been maintained 

 that these are particles or strands of chromatin emitted 

 from the nucleus, and their existence gave rise to the hy- 

 pothesis that the nucleus contains two kinds of chromatin, 

 " idiochromatin " concerned especially with reproduction 

 and heredity, and " trophochromatin " with metabolism, an 

 idea based on the extrusion of "chromidia" from the repro- 

 ductive nucleus of many Protozoa and the existence of 

 separate mega- and micro-nuclei in the Ciliates 1 . The 

 chromidial bodies of certain Metazoan cells were thus sup- 

 posed to be trophochromatin discharged from the nucleus 

 in order to perform its metabolic functions in the cytoplasm. 

 That bodies which stain like chromatin occur not uncom- 

 monly in the cytoplasm is undoubted, but their origin from 

 the nucleus is by no means certain, and their true nature is 

 still obscure. Some of the so-called chromidial bodies are 

 also quite probably in reality mitochondrial rather than 

 chromatinic in origin. 



1 See C. C. DOBELL (1909). 



