PL AST IDS AND CHONDRIOSOMES -115 



cycle in some less conspicuous form. If they represent regional trans- 

 formations of the cytoplasm resulting from the localization of certain 

 processes, they might well be expected to differentiate anew as these 

 processes begin in the life of the cell, and to preserve varying degrees 

 of permanence depending upon the processes carried on (Harper). 

 Their individual continuity through certain life cycles would accordingly 

 be interpreted to mean that in such forms there is a persistence of certain 

 types of physiological activity through all stages. 



In recent years a number of cytologists have described the develop- 

 ment of plastids from minute granular primordia in the cytoplasm, and 

 have attempted to show that these primordia are members of the class of 

 cell inclusions known as chondriosomes. A general theory of the indi- 

 viduality of the plastid must therefore involve the question of the relation 

 of plastids to chondriosomes, and the further question of the origin of the 

 chondriosomes themselves. These matters will be taken up in the fol- 

 lowing pages. 



CHONDRIOSOMES 



Notwithstanding the large amount of work which has been done upon 

 chondriosomes during recent years, the condition of opinion as to their 

 origin, behavior, and significance is still so unsettled that little more than 

 a review and partial classification of the more prominent views will 

 here be attempted. 



Chondriosomes were probably first observed many years ago by 

 Flemming and Altman in the course of their studies on protoplasm. 

 They were first clearly described by La Vallette St. George (1886), who 

 observed them in the male cells of animals and called them "cytomicro- 

 somes." In plants they were first described by Meves (1904) in the 

 tapetal cells of the anthers of Nymphcea (Fig. 43, B). Benda in 1897 

 and the following years discovered them in cells of many types, notably 

 in the spermatogenous cells of animals, and applied to them the term 

 "mitochondria." It was not until a decade later, through the researches 

 of Meves, Regaud, Faurd-Fremiet, Lewitski, Guilliermond, and others 

 that they came into prominence. Since that time they have been very 

 intensively studied by both zoologists and botanists, and a special 

 literature of considerable bulk has developed. 1 It now seems evident 

 that the filaments ("fila") of Flemming, the "bioplasts" of Altman, the 

 " plastidules " of Maggi, the " archoplasmic granules" of Boveri, and the 

 "mitochondria" of Benda are all one and the same thing chondriosomes 

 (Duesberg 1919). 



General Nature and Occurrence. Chondriosomes occur in the cyto- 

 plasm of the cell, commonly in the form of minute granules, rods, and 



1 Reviews of the subject are given by Duesberg (1911, 1919), Schmidt (1912), 

 Cavers (1914). and Guilliermond (1919). See also MevQ$ (1918). 



