No. 375.] REVIEWS OF RECENT LITERATURE. 205 
Dr. Deniker believes that he has established a basis upon which 
to build deductions from the facts relating to archeology, topography, 
linguistics, etc. It will be noticed that his preliminary conclusions 
differ materially from the final results of Professor Ripley’s careful 
studies. We shall await with interest for further accounts of Dr. 
Deniker’s work ; it may assist in establishing the true value of the 
data upon which the Anthropo-sociologists, Ammon, Lapouge, and 
all “these head fellows” depend. At present this mathematical 
method seems to be too seductively easy. FRANK RUSSELL. 
ZOOLOGY. 
The Development of Fresh-Water Bryozoa.'!— Another grand 
quarto on fresh-water Bryozoa by Braem. As many observations of 
broad interest are included in this work, it is desirable that especial 
attention should be directed to them. 
Spermatogenesis. The spermatogonia contain a large nucleus 
with one or two nucleoli and a “Nebenkern.” The number of 
chromosomes in the first division was not exactly made out; it was 
between twelve and sixteen. During the second division the number 
is smaller (six to eight), so that the first is doubtless the reducing 
division. The cytoplasms of a large number of spermatids fuse 
into a single mass; the axial filaments of the tails arise and are of 
cytoplasmic origin; the neck is formed by the aggregation at one 
point of microsomes that were previously scattered all about the 
nucleus; the head arises from the nucleus in that the chromatin first 
accumulates at one pole, then the nuclear sap is eliminated, and the 
whole body becomes smaller and dense. An erythrophile substance 
also passes from the nucleus into the cytoplasm. 
The ovarian eggs have a nucleolus which is often dumb-bell- 
Shaped or double and contains one or more contracting vacuoles. 
The cytoplasm exhibits two concentric zones, of which the outer 
contains large, deeply staining granules of unknown origin. Matura- 
tion stages were not observed. 
fertilization takes place in the ovary. The egg then passes into 
an “oœcium,” —a modified polypide,—to the wall of which the 
Ovary may be said potentially to belong. 
1 Braem, F., Die geschlechtliche Entwickelung von Plumatella fungosa. Zoo- 
logica, Heft 23, 96 pp., 8 plates. 
