20 THE VARIATIONS AND CORRELATIONS OF 



differences upon the soil-selection hypothesis, and the differences are in 

 the direction which this idea would require. These things, taken in con- 

 nection with what follows, make a fairly good case for this contention. 



Blatchley's species, arenaceus, is characterized by a long ovipositor 

 as compared with the body and tegmina. As its name implies, it is 

 "sand-loving." Blatchley found it in "bare sandy places" in the dune 

 region of Lake Michigan. The poor food-supply in such places would 

 easily account for its small body and tegmina, but why was not the 

 ovipositor reduced also? It seems to me that we have a sufficient 

 answer in the necessity of the creatures' laying their eggs deep in the 

 sand. If the ovipositor were not long, the eggs wintering over nearer 

 the top of the sand would be much exposed to the rigorous climatic 

 conditions of the dune region, even if they were not actually uncovered 

 by the shifting of the sand. It seems to be an adaptive reponse, brought 

 about by selection, to the condition of the soil, just as in the Cold 

 Spring Harbor collections, and, in this case, it gave rise to a "species." 



In most localities there is an early-summer-maturing group and a 

 fall-maturing group or brood. These are supposed not to interbreed. * 

 The members of the early-maturing group usually have shorter ovipos- 

 itors than those of the late-maturing one. The former includes penn- 

 sylvanicus and americanus; while arenaceus, abbreviatus, and firmus 

 make up the latter group. Compare in this connection the two Orono, 

 Maine, collections: October, 1904, average ovipositor-length, 12.9; June, 

 1905, 11.1. The average ovipositor-length at Gotha, Florida, Septem- 

 ber, 1903, was, short-winged 15.7, long-winged 16.5. The June, 1904, 

 brood at the same place gave 14.6 and 16.4, respectively. I think we 

 have here again a simple adjustment of the length of the ovipositor to 

 environmental conditions, the long-ovipositored group having to winter 

 over in the egg state, while the eggs of the short-ovipositored group 

 develop in a few weeks in midsummer. 



These three lines of evidence the Cold Spring Harbor and Perkins 

 Cove collections, the unconscious testimony of a taxonomist, and the 

 relation between the summer-maturing and the fall-maturing groups- 

 seem to indicate that the length of the ovipositor is a function of soil 

 and weather; also that the active factor in the equation is selection. I 

 am attempting to study this point experimentally, but at the best will 

 not be able to report for several years. 



Concerning the relations between the other organs and local condi- 

 tions of the environment, I have at present little definite to offer. The 



*I doubt this, as all of the fall-maturing group which I have been rearing in a 

 cool, shady place are still (in October) immature and will not mature before next 

 spring, when they will have a chance to mate with individuals of the summer-maturing 

 group. 



