NATURAL SCIENCES OF PHILADELPHIA. 277 



As vrc know from the expei-iments of Hogg, Dumeril and otbers that met- 

 amorphosis is greatly hastened or dehiyed by the conditions of temperature 

 and liglit, whai would not be the effect on such a protean species of a change 

 of topographical situation, such as the elevation or depression of the land ? 

 And f have no hesitation in saying that if the peculiarities of series of indi- 

 viduals of A. tigrinum and A. raavortiuiu, in the respects above 

 enumerated, were permanent, they would characterize those series as species, 

 as completely as any that zoologists are accustomed to recognize. For the 

 evidences on this head, see the discussions of those species in my raonogiaph. 



The experiments of Hogg above alluded to, are as follows, as given by him 

 in the Annals and Magazine of Natural History. 



He placed a number of impregnated ova of frogs in vessels arranjied at reg- 

 ular distances from the light, in a cave. The lessening degrees of light were 

 of course accompanied by a corresponding but much less rapid decline in 

 tem])erature. The resulting effects on the metamorphosis may be taliulated 

 as follows : 



Mo. day. (30° 5G° 53° 51° 



~3 n Eg^: Egg: ig^. e^. 



20 Larva free, * * * 



25 * Larva free, * * 



31 * * Larva free, Larva free, 



4 10 Larva very large, * * * 



'J'2 Metam. complete. Larva large, Larva large. Larva small, 



8 11 Metam. complete, * * 



28 Metam. complt. * 



10 31 Metam. comp. 



3. The reproduction of some species of insects before they complete their 

 metamorphosis is a well-known fact, and it is particularly to the point that, 

 in many -of them, some individuals do attain to their full development, while 

 the many do not. Westwood says,* " two British species of this family (the 

 Reduviida;), Prostemma g u 1 1 ul a and Coranus subapterus, are interest- 

 ing on account of their being generally found in an undeveloped state, the 

 latter being 'either entirely apterous or with the fore-wings rudimcntal, 

 although occasionally met with having the fore-wings completely developed. 

 '"1 think," says tipiuola, "that the presence of wingsand their development de- 

 pends on the climate," and in speaking of Oncocephalus g r i s e u s, he says 

 " the inrtuence of the northern climate appears to have arrested the develop- 

 ment of the organs 'of flight." It will be seen that I have referred elsewhere 

 that I have noticed that it is especially in hot seasons that certain species 

 acquire, while the circumstance noticed respecting the ordinary occurrence of 

 winged specimens of Microcoelia in the West indies is confirmatory of the 

 same opinion." 



4. It is now known that certain Orthoptera do not get through their meta- 

 morphosis in time for the period of reproduction, and hence never or in rare 

 instances only devclope more than a short distance beyond the pupa state. 



5. .My friend, P. R. Uhler, tells me of an example among Hemiptcra of 

 the genus Velia. The species V. r i v u 1 o r u m Fab., and V. c u r r c n s* of 

 Europe, are only distinguished by the developmental feature of the presence 

 of wings in one, and their absence in the other. Another species of the tropi- 

 cal region of the West Indies, Halobates a m e r i c a n u s Uhlcr, is furnisiied 

 with wings, while its individuals which occur abundantly in North America 

 have been generally supposed to lack them. Individuals, however, no doubt 

 occur whose developments is so far accelerated as to permit them to acquire 

 wings before the period of reproduction, since one such has been found by 

 Uhler. 



* Uhler informs me that Amyot's asserted color characters are not reliable. 



1868.] 



