THE GERM-CELLS OF CICADA (TIBICEN) SEPTEMDECIM. 45! 



presence of one large pair of chromosomes (the macrochromosome 

 pair, AA} and two pairs of somewhat smaller chromosomes 

 (BB, CC}. The other 13 chromosomes show no size differences. 



3. There is no variation in chromosome number or in their 

 form and arrangement in any of the diploid groups studied. 



4. In the spermatocytes there are two ring tetrads of the 

 Stenobothrus type, which are derived from the A A and BB 

 chromosome pairs of the spermatogonia. These tetrads divide 

 reductionally in the first maturation division. 



5. An odd chromosome is present which persists as a nucleolus 

 in the growth stages of the spermatocyte. It passes undivided 

 to one pole in the first maturation division and divides in the 

 second division. 



6. The tetrads are always grouped characteristically in the 

 metaphase of the first maturation division and the same grouping 

 is found in the metaphase of the second spermatocytes. 



7. The synaptic stages in the oocyte were studied, giving 

 evidence that the chromosomes pair side-to-side (parasynapsis). 



8. Two chromatin nucleoli are present in the preleptotene 

 stages of the oocyte. These disappear in the synaptic stages and 

 reappear in the post-synaptic stages. These nucleoli are inter- 

 preted to represent the two sex-chromosomes of the female 

 w r hich go through a synaptic phase like the autosomes. 



9. Mitochondria are found in the spermatogonia in the form 

 of granules localized at the end of the cell bordering on the cyst 

 cavity. 



10. The first evidences of a degeneration of a spermatogonium 

 is shown by an agglutination of the mitochondria. As degenera- 

 tion continues the mitochondria continue to agglutinate forming 

 large lipoid globules in the cell, evidently yielding a fatty de- 

 generation. 



11. In the spermatocytes the mitochondria are filar; they 

 surround the spindle peripherally at the time of the maturation 

 divisions and become divided by the cell-constriction. The 

 mitochondria of the spermatid form the round compact Neben- 

 kern which later becomes drawn out as a sheath surrounding the 

 axial filament of the spermatozoon. 



12. The ovaries of Cicada are typically Hemipteran in struc- 



