76 The American Naturalist. [January, 
while the ectoderm is internal! If, discouraged at this result, we decide 
to regard the germ layers as occupying the same relative position in the ; 
Spongilla larva as in the larvæ of other Metozoa, and therefore call the — 
superficial layer of ciliated cells ectoderm, and the inner mass of cells 
entoderm, we reach the equally strange conclusion that the adult — 
epidermis is composed of entoderm, while the lining epithelium of the : 
flagellated chambers is formed of ectoderm! The only way out of the — 
dilemma is to regard the sponges as a phylum which has followed from — 
the start a path of development distinct from that of Ccelenterates and _ 
other Metazoa. This being so, a comparison of layers is impossible. 
V. WILSON. 
Development of the Newt.—Edwin Oakes Jordan’ presented 
for the Ph. D. degree at Clark University a study of the common — 
newt Diemyctylus viridescens Raf., that contains a very clear account of 
the maturation of the ovum, fertilization, cleavage, and formation and 
fate of the blastopore in addition to many new facts in the breeding 
habits of this interesting amphibian. 
The “ yolk nuclei” are considered at some length and regarded as 
“having a real physiological significance, probably related to the con- — 
struction of yolk.” _In this formation of yolk there is “ nothing to im 
dicate that the yolk spherules increase by division, everything on the — 
contrary indicates that they arise from points of independant origin.” 
The nucleoli in the egg nucleus are described in their formation and — 
disintegration and the idea advanced that they may be but enlarg: 
ments of the minute granules making up the chromatin threads. 
Regarding the nucleoli as of nutritive function, acting during the 
some, but none could be found. Much in the same way the entering 
sperm, in fertilization seems to exhibit an attractive influence over the 
. Pigment granules. Elsewhere, however in speaking of the gastrula, 
the author supposes that pigmentation of the cells is a mark of physio- 
3 logical activity ; so that we are left in doubt as to how for an appal : 
ent attraction of pigment may be a new formation of it. : 
_ In the account of the process of fertilzation we learn that there is n0 
xed and predetermined point of entrance of sperm and moreover 
pia may, in fact normally do, enter one ovum without in any way 
causing abnormal development, T ee 
Journal of Morphology. VITT. 1893. 
