472 D. H. WENRICH 



I. INTRODUCTION 



In a recent paper (Wenrich, '16) the writer presented what 

 seemed to him conclusive evidence that parasynapsis occurs 

 in at least three pairs of first spermatocyte chromosomes of 

 Phrynotettix magnue. Although only these three chromosomes 

 were studied in great detail, sufficient attention was given the 

 other members of the complex to assure the writer that para- 

 synapsis occurs in all. Phrynotettix, however, like many of the 

 Oedipodinae, possesses only rod-shaped, or telomitic chromo- 

 somes. It seemed advisable, therefore, to investigate the con- 

 ditions to be found in species of grasshoppers in which the 

 chromosomes are V-shaped, or atelomitic. Chorthippus (Steno- 

 bothrus) curtipennis was chosen for this study because it is 

 readily obtainable, gives clear figures when fixed and stained, 

 and because various species of the genus have been the subject 

 of investigation in the past. Sufficient study of this species, 

 which has three pairs of atelomitic chromosomes, was made be- 

 fore the publication of the paper on Phrynotettix to assure the 

 writer that the chromosome relationships in synapsis are essen- 

 tially the same as in that form with respect to both types of 

 chromosomes. This is indicated by the following statement 

 (Wenrich, '16, p. 98): 



I have recently made a study of the conditions in Stenobothrus and 

 may say that I found parasynapsis for both forms of chromosomes, 

 and that the V-shaped chromosomes divide reductionally in the first 

 maturation mitosis as Davis ('08) described, but that the rod-shaped 

 chromosomes divide equationally in the first division as I found that 

 they did in Phrynotettix. 



No drawings were presented to support these statements at 

 the time, but the evidence (with additions) on which the conclu- 

 sions as to parasynapsis were based is presented in the present 

 paper. Unfortunately, more careful study of the material makes 

 it impossible to be so confident as to which division is reductional 

 for the two types of chromosomes. This point mil be discussed 

 later. 



The same conclusions as to parasynapsis in Chorthippus, to- 

 gether with the same kind of evidence, in part, has recently 



