THE GERM-CELLS OF CICADA (TIBICEN) SEPTEMDECIM. \2 



in the giant spermatocytes (Fig. 59) the mitochondrial content 

 is-much greater than in the normal cells and the giant spermatids 

 derived from such giant spermatocytes have Nebenkerns which 

 are correspondingly larger than the normal ones (compare Figs. 

 30 and 31). 



(c) Transformation of the Spermatid. Besides the deeply stain- 

 ing Nebenkern, there are also present in the cytoplasm of the 

 spermatids, an acrosome-sphere, a centrosome and often a 

 chromatoid body (Fig. 30). The latter is found in some of the 

 spermatogonia and some of the spermatocytes, passing undivided 

 to one of the daughter cells at the time of mitosis. During the 

 transformation of the spermatid, the chromatoid body is cast off 

 in the elongating tail, as has been described by Wilson ('13) in 

 Pentatoma. 



The centrosome of the spermatid is derived from the centro- 

 some of the second maturation division. In the late anaphase 

 (Fig. 29), the centrosomes lie close to the chromatin masses at 

 both poles and in the telophase, when the spermatid nucleus is 

 reconstructed, it can still be seen closely adhering to the surface 

 of the nuclear membrane (Fig. 30). The axial filament begins 

 to grow from the centrosome and pierces the Nebenkern (Fig. 

 32). The division of the Nebenkern into two halves lying on 

 each side of the axial filament is not quite so clear as in the case 

 of other insects. In the further elongation of the spermatid 







(Fig. 33), the Nebenkern becomes drawn out, as the axial filament 

 grows, into two narrow filaments forming a sheath around the 

 axial filament. 



What I have termed the "acrosome-sphere" is a derivative of 

 the spindle; but w r hether it represents the "sphere" material or 

 whether it is a portion of the mitosome could not be determined. 

 It is a rather large compact body and stains intensely with 

 haematoxylin. (Figs. 30, 32). As the spermatid goes through 

 the stages of transformation, the acrosome-sphere becomes some- 

 what compressed and forms a typical acrosome at the head of 

 the spermatozoon. 



(d} Discussion. Leaving aside for the present the question of 

 the origin of the mitochondria, let us turn to consider some of the 

 facts concerning the behavior of the mitochondria in spermato- 



