452 The American Naturalist. [May, 
originally suggested by H. W. Bates; a variety of changes which occur 
are explained by this theory and by no other yet propounded. Local 
changes may be explained in many ways; but that they should invari- 
ably be in the direction of a superficial resemblance to one butterfly, 
and that one a specially defined species, is only to be explained by the 
theory of mimicry. Although much support has been afforded to this 
theory since Bates propounded it in 1862, Col. Swinhoe states that no 
evidence is so complete and convincing as that supplied by the genus ~ 
Hypolimnas. If we are right in believing that the results are deter- 
mined by the range and abundance of mimetic forms, it is clear that 
selection, rather than unguided variation, is the essential cause of the 
phenomena.—Journ. Royal Microscop. Society. 
Remarkable Vitality.—Early in September, 1896 I collected 
two forms of life from Great Salt Lake, one was the brine shrimp Ar- 
temia fertilis, the other the larva of a fly, the Ephydra gracilis. 
After keeping these in salt water for ten days I washed them in fresh 
water, and then placed them in a small vial filled with a 3 per cent. 
solution of formaline. 
After they had been in this solution for ten days I had occasion to 
examine them, and on taking them from the vial I found that three of 
the Ephydras were still living and active. The vitality of the Ephydra 
seems to be fully equaled by the vitality of the Stenophelmatus fasciatus 
order Orthoptera. Some fragments of this insect were sent to the 
University of Utah for identification. Among the fragments was the 
prothorax bearing the head. This piece lived for nine days, and dur- 
ing that time when ever it was irritated would attempt to bite with its 
powerful jaws. It would also turn over into its natural position when 
placed on its back —C. A. WHITING. 
EMBRYOLOGY. 
Two animals from one egg.—To the many known cases in 
which two animals may be obtained from one egg by experimental > 
interference, may now be added the amphibian Triton cristatus. BY 
the aid of a simple piece of apparatus Amedeo Herlitzka’ succeeded 1D — 
1 Edited by E. A. Andrews, Baltimore, Md., to whom abstracts, reviews and 
preliminary notes may be sent. ‘ 
2 Archiv f. Entwicklungsmechanik. IV, März 2, 1897, pps. 624-654, pl. 27. 
