86 INTRODUCTION TO CYTOLOGY 



required to reach the typical size; he also observed actual division several 

 times. From his observations on myxomycetes (fixed material) Lewitsky 

 (1924) concluded that the chondriosomes, which are capable of division, 

 may become progressively smaller until they pass below the limit of 

 visibility, and that by growth they may pass the limit in the reverse 

 direction, giving the appearance of origin de novo. This places the 

 problem of ultimate origin in the realm of the invisible. 



The behavior of the chondriosomes at the time of nuclear division and 

 cell-division varies widely in different cases. In somatic tissue cells 

 their distribution is quite fortuitous, though approximately equal if the 

 cytoplasm is equally divided. In microporocytes the chondriosomes tend 

 to group about the nucleus and the mitotic figure and are apportioned 



more or less equally to the four spores (Figs. 44, 

 45). In Nephrodium they form an equatorial 

 layer between the two nuclei after the first divi- 

 sion; this layer is then divided into four parts by 

 the developing cell membranes. ^^ In the living 

 I spermatocyte of a grasshopper, Dissosteira Caro- 

 lina, Chambers (1915) saw the chondriosomes 

 form a mantle about the nucleus, the mitotic 

 figure, and the daughter nuclei, much as in the 

 Fig. 45.— Young spore niicrosporocyte of Larix (Devise, 1922) (Fig. 82). 

 quartet of Nephrodium, In other Spermatocytes the chondriosomes are 



showing cell partition j. i ]l i ■ t • i i t • ■ j-j^ xi 



formed in mitochondrial reported to Undergo mdividual division after the 

 layer. {After Senjaninova, division of the chromosomcs.^'* In EuscMstus the 



chondriosomal filaments lying across the equator 

 of the cell are passively cut in two by the constriction furrow as the cell 

 divides^^ (Fig. 129), but in Gryllotalpa borealis they appear to break and 

 move apart before the furrow appears (Payne). In Gryllotalpa vulgaris, 

 Voinov (1916, 1925) states that the "mitochondria" fuse to form a thread 

 which then segments into 60 or more "chondriosomes. " These units are 

 arranged in the spindle along with the chromosomes, which they may 

 resemble, divide at both meiotic mitoses, and are thus equally distributed 

 to the four resulting spermatids (Fig. 46). 



In certain scorpions the chondriosomal material of the spermatocyte 

 is distributed with remarkable precision (Wilson, 1916). In Centrums 

 it takes the form of a single ring-shaped body which lies by the side of 

 the spindle figure. The ring divides accurately at both meiotic divisions 

 along with the chromosomes, each of the four spermatids, and hence each 

 spermatozoon, receiving a quarter of its substance. In Opisthacanthus 



13 Senjaninova (1927c). Cf. Yamanouchi (1908a). See also Lewitsky (1925) on 

 Equisetum. 



" Faur6-Fremiet (1910a), Korotneff (1909), Terni (1914), Payne (1916). 

 16 Montgomery (1911), Bowen (1920). 



