486 E. ELEANOR CAROTHERS 



hand a supernumerary ought contain the locus for multiple 

 allelomorphs, in which case it might have an influence. The 

 varying sizes found are perhaps due to two causes: (1) origin 

 from different tetrads, (2) degeneration. More than one-fourth of 

 the population of form 'B' contain supernumeraries, and, though 

 one would expect that they would automatically pile up, no 

 individual has been found with more than two. It therefore 

 seems evident that there must be some method of elimination. 

 Wilson ('09) believes the supernumerary chromosomes in 

 the Hemiptera tire additional small idiochromosom.es, and 

 states that they are about the same size, of like behavior and 

 show (Wilson, '07^ some degree of coupling with the small 

 idiochromosome. The supernumeraries found in the course 

 of my work could not have had such an origin, since the sex- 

 determining mechanism in the grasshopper is the accessory and 

 not an X-Y pair. They are constant in size in a given individual, 

 but range in different individuals from the size of the accessory 

 (plate 9, t>2^ to less than a fourth of that size. In behavior 

 during the growth period they simulate the accessory. If "Wil- 

 son's hypothesis (that they are derived from the sex chromosome* 

 were correct, my individual number 62, which appeared to be 

 an entirely normal male, should have been a female; for the 

 essential difference between the sexes is the possession of two 

 accessories by the female, and in this particuar case the super- 

 numerary, in the first spermatocyte metaphases simulates the 

 accessory so closely both in size and appearance, that it is some- 

 times difficult to decide which is which. It seems probable 

 that it was a large supernumerary oi this type that Davis ('08) 

 confused with the accessory when he described two 'monosomes' 

 (accessories) as being present in one specimen of Arphia tene- 

 brosa (p. 102). 



3. Ta.vonomic variability and gametic composition of the group 



My own slight knowledge of taxonomy, together with a 

 recognition of similarity of habits and environment acquired 

 through field work, enabled me to group these related forms as 

 they were collected. The specimens were later turned over to 



