530 The Adaptive Range of the Batrachians, [September, 
such flies must live and die without ever having partaken of 
human blood, or of human secretions whatsoever. Why, 
then, are they so persistently eager for what is not necessary 
to their existence, and what, in many cases, they and their 
forefathers have never tasted ? 
If, as is now generally admitted, these beings are more- 
over the pedlers of disease, can the teleologist pronounce 
their existence, if purposive, as other than malignantly so ? 
And if they have arisen without purpose, on the principle 
of Natural Selection, the difficulties of the case are not 
smaller. 
IV. THE ADAPTIVE RANGE OF THE BATRA- 
CHIANS, AND THE CORRELATION 
OF ORGANS. 
By Dr. J. Kollmann. 
S HE power of adaptation to different surrounding cir- 
cumstances is strikingly developed in the Batrachians. 
According to established fafts the range within which 
their organism can accommodate itself to novel relations is 
more extended than that of any other vertebrate animal, 
and its limits are by no means ascertained. As the most 
striking example may be mentioned the results of Miss von 
Chauvin, who by artificial means kept back four axolotls for 
three years in an intermediate stage, in which the nature of 
the water-newts and that of the Amblystomas are so blended 
that the animals can live either in or out of water. The 
newt, formerly regarded as perennibranchial, as the most 
recent intelligence from South America shows, can after the 
lapse of a year become terrestrial, as soon as circumstances 
demand. But it may be retained in an intermediate stage 
of development, and its organism can exist as the Siredon. 
Yet more ; its organism can rise to the highest stage of its 
capacity for development, become terrestrial, throw oft its 
gills, evolve lungs, and become adapted for life on the dry 
land! Still, if desirable, it can lay aside its terrestrial cos- 
tume just completed, and resume its fish-nature. Alter the 
