172 Jeffries Wyman. 
that, whatever view be taken of their homology, they are 
something superadded to it, and not evolved from it; he notes 
how the whole yelk-mass is moulded into a spiral intestine; 
and that the embryo at the end of incubation forms a larger 
and heavier mass than existed in the egg when it commenced, 
—showing that there was an absorption of material furnished 
the dermal sac of the mother,—‘‘a solitary instance among 
Batrachians, if not among Reptiles generally, in which the 
embryo is nourished at the expense of materials derived from 
the parent.” From this he is led (in the later paper above 
mentioned) to infer the probability that the developed larve 
of Hylodes lineatus,—carried about inland upon the back of 
their mother, and destitute of limbs adapted to terrestrial loco- 
motion,—may depend upon a secretion from the body for need- 
ful sustenance—an interesting and rudimentary foreshadowing 
of mammalian life, of which he discerned the bearings. 
His “Description of a Double Foetus” (in the Boston Med- 
ical and Surgical Journal, March, 1866) gives him the oppor- 
tunity of briefly recording some of the results of his studies of 
the development of double monsters, and to bring out his view, 
that “the force, whatever it be, which regulates the symmet- 
rical distribution of matter in a normal or abnormal embryo, 
has its analogy, if anywhere, in those known as polar forces;” 
that “studying the subject in the most general manner, there 
are striking resemblances between the distribution of matter 
capable of assuming a polar condition and free to move around 
a magnet, and the distribution of matter around the nervous 
axis of an embryo.” 1at this is not one of those vague con- 
ceptions by which many speculators set about to explain that 
of which they know little by means of that of which they 
ow less, but that he had striking parallelisms to adduce, the 
close of this striking paper shows. : 
The subject of fore and hind Barges 8 thus brought di- 
r. 
speculative morpholo 
n’ 
= 
