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INTRODUCTION TO CYTOLOGY 



believe that they have found good evidence for the view that chondno- 

 somes may multiply by division, and some (Guilliermond ; Moreau 1914; 

 Terni 1914) have held this to be their sole mode of origin that they arise 

 only from preexisting chondriosomes and are therefore permanent cell 

 organs. Others are convinced that they may arise de novo in the.cyto- 

 plasm, and that the evidence for their division is unsatisfactory (Orman 

 1913; Lowschin 1913; Scherrer 1914; Miss Beckwith 1914; Chambers 

 1915; M. and W. Lewis 1915: Twiss 1919; and others). The investiga- 

 tors of the foregoing group, together with Meves (1900), Lewitski (1910), 

 and Forenbacher (1911), hold that the chondriosomes arise from the cyto- 

 plasm, but certain others believe they take their origin from the nucleus. 

 Tischler (1906) and Wassilief (1907), for example, state that they arise 

 from surplus chromatin. Alexieff (1917) thinks that although cyto- 



FIG. 44. Examples of regular behavior of chondriosomes in cell-division. 

 A-C, spermatocyte of Gryllotalpa vulgaris, (After Vo'inov, 1916): A, chondriosomal 

 material in cytoplasm about nucleus; B, heterotypic mitosis, showing chondriosomes (at 

 sides) occupying the spindle with the chromosomes (at center); C, stages in the division 

 of a chondriosome. D, Dividing cell of Geotriton fuscus, showing division of individual 

 chondriosomes as cell constricts at equator. (After Terni, 1914.) 



iplasmic dfferentiation is due to them, .they are at least in some cases 

 of nuclear origin ; and further that they are not fundamentally different 

 from chromosomes and chromidia, a conclusion contradictory to that of 

 Duesberg and E. V. Cowdry, cited above. Shaffer (1920) believes them 

 to arise as the result of a chemical action of the nucleus upon products of 

 assimilation in the adjacent cytoplasm. Wildman (1913) classifies the 

 cytoplasmic inclusions present throughout spcrmatogenesis in Ascaris 

 into two main types, both of nuclear origin: "karyochondria," equiva- 

 lent to the mitochondria of other writers, and ",plastochondria," which 

 pass into the cytoplasm, form yolk within them, and fuse to form the 

 food supply ("refractive body") of the spermatozoon. 



That the behavior of the chondriosomes at the time of cell-division 

 is a matter of considerable importance has been generally recognized. In 

 many cases their distribution to the two daughter cells seems to be quite 

 fortuitous, whereas in some tissues more or less definite modes of distribu- 

 tion have been described. According to Faure-Fremiet (1910), Terni 

 (1914), Korotneff (1909), and others, the individual chondriosomes divide; 

 at the time of mitosis (Fig. 44 -, D), a conclusion with which many others 

 fail to agree (Orman 1913; Miss Beckwith 1914; etc.). In the cells of 



