THE GERM-CELLS OF CICADA (TIBICEN) SEPTEMDECIM. 423 



the male and female germ-cells, namely, after synapsis and before 

 the appearance of the definitive maturation tetrads. 



D. OBSERVATIONS ON MITOCHONDRIA. 1 

 i. Mitochondria in Spermatogenesis. 



(a) Spermatogonia. Mitochondria are present in the sperma- 

 togonia of all stages in the form of granules usually localized 

 at one end of the cell, usually the end directed toward the cyst 

 cavity (Fig. 13). This is quite the usual location of mitochondria 

 in spermatogonia, but as I have shown in Passalus (Shaffer, '17), 

 the mitochondria may be diffusely spread in the cytoplasm. 

 There is no indication that the mitochondria of the spermato- 

 gonia ever assume the form of filaments. During mitosis the 

 mitochondria are spread along the outer spindle-fibers and by the 

 time of the telophase and the cell-constriction, the mitochondria 

 become grouped as granular masses lying above the daughter 

 nuclei. 



The amount of cell-degeneration taking place in the testes of 

 Cicada was so striking as to call for more than mere casual 

 observation. Sometimes an entire half of a follicle would be 

 filled with cells in various stages of degeneration. This degenera- 

 tion is usually found only among the spermatogonia prior to the 

 commencement of the growth stages of the spermatocyte, which 

 seems to be a critical time for the cells. Once they begin the 

 synaptic processes, they apparently go through to maturation 

 normally. It is quite noticeable that cell-degeneration is more 

 abundant in the adult testes than in the testes of pupae. 



1 I shall continue to use the term "mitochondria" to denote those cytoplasmic 

 structures, regardless of their form, which are preserved by special reagents 

 (destroyed by acetic acid, etc.) and which take specific stains. I see no advantage 

 in the employment of the term "chondriosome" as recently urged by Duesberg 

 ('19). The term "mitochondria" is not only more commonly used in this country 

 but also conveys the idea of their nature quite as well as "chondriosome." It can 

 be equally well applied to those structures when filar in form as when granular and 

 it seems to be etymologically as proper as the term "chondriosome." The various 

 names which have been proposed to designate these structures (chondrioconts, 

 plastosomes, plastidules, karyochondria, etc.) are based either upon their supposed 

 origin or else upon their morphology. Since there is still much confusion as to 

 their origin and since their morphology may vary at different times in the cell-cycle, 

 it seems best not to commit ourselves to the use of new terms but to employ the 

 original name, "mitochondria," of Benda. 



