ORTHOPTERAN SPERMATOGENESIS 655 



THE SPERMATOGONIAL CHROMOSOMES 



a. Hippiscus type 



It is aside from the purpose of the present paper to enter far 

 into a discussion of conditions in this generation of the germ cells. 

 In order that the facts may be before us it will however be neces- 

 sary to state briefly what is known about the chromosomes at 

 this time. For details reference should be had to Sutton's ('00) 

 paper. A polar view of a spermatogonial metaphase shows 23 

 elongated, rod-shaped chromosomes, arranged radially about 

 the spindle axis with fiber attachment at the inner end (figs. 

 20, 44, 77, 94, 98). In the anaphase the chromosomes separate, 

 beginning at the inner end, and move to the poles of the spindle 

 as simple straight rods. Later they lie side by side, approxi- 

 mately parallel, and become vesicular, with the chromatin on the 

 periphery. During the prophase of the succeeding mitosis the 

 chromatin contracts to the center of each vesicle and the defini- 

 tive chromosomes of the late prophase reappear in the same 

 relative positions they occupied in the preceding telophase. The 

 cells of one young Chortophaga nymph showed an interesting 

 modification of this condition. The largest four pairs, instead 

 of being separate, were joined together at their ends and appeared 

 in the form of tetrads with the fiber attachment at the point of 

 junction (fig. 94). In the anaphase each chromosome com- 

 menced to divide, as usual, at this point and in these cases the 

 anaphase chromosomes were V-shaped with the apex (synaptic 

 end) directed towards the pole of the spindle. All the cells of 

 this individual showed the same conditions. 



b. Stenobothrus type 



Exceptions to many general conditions are found in the appear- 

 ances presented by the cells of Stenobothrus. This is a genus 

 that has been extensively studied and, in general, correctly inter- 

 preted. Because of its exceptional nature many generalizations 

 based upon it are wrong. This will appear clearly as the dis- 

 cussion proceeds. To avoid confusion I shall, throughout this 



