— 
784 SCIENCE. 
appearance the chromatophores are found only 
in the mesoderm. They are single cells with a 
single large nucleus, appearing to be multi-nu- 
clear only when in degeneration they are in- 
vaded by adjacent connective-tissue cells. The 
author explains the expansion of the cells by 
the contraction of the radial fibers around it 
and its contraction by the elasticity of the cell 
membrane. 
Other papers are by Herr Thon on ‘The 
Copulatory Organs of the Hydrachnid Genus 
Arrhenurus Dugés’; by Dr. Doflein on ‘The 
Inheritance of Cell Characteristics’; by Dr. 
Simroth on ‘Self-Fertilization in Pulmonates’; 
by Dr. Escherich on ‘The Germ Layers in the 
Muscide’; and a history and description of the 
Graz ‘ Zoologisch zoolomische Institut,’ by Pro- 
fessor L. v. Graff. : 
The excursion of this session was made to the 
Austrian Zoological Station at Trieste founded 
twenty-five years before, largely through the 
efforts of Professor F. E. Schultze. Since the 
retirement, in 1896, of Professor Carl Claus, 
director of the station for many years, the con- 
trol of the enterprise has been in the hands of 
a board representing the leading Austrian uni- 
versities. With the change has come renewed 
activity, an.enlarged building and increased 
equipment. 
CHARLES A. KOFOID. 
UNIVERSITY OF CALIFORNIA. 
A Select Bibliography of Chemistry 1492-1897. 
By HENRY CARRINGTON BOLTON. Section 
VIII. — Academic Dissertations. City of 
Washington: published by the Smithsonian 
Institution. 1901. Pp. iv + 534. 
This volume—number 1253 of the Smith- 
sonian Miscellaneous Collections—is the third 
in Dr. Bolton’s ‘ Bibliography of Chemistry.’ It 
is devoted exclusively to those academic disser- 
tations which have been printed independently, 
and especially to those from the universities of 
France, Germany, Russia and the United States. 
The number of the last is exceedingly small, 
for it seems not yet to be the custom of most 
American universities to require the printing of 
theses for the doctor’s degree, although much 
of this work finds its way sooner or later into 
periodical literature. About seven thousand 
[N.S. Von. XIII. No. 333. 
dissertations are catalogued in the volume, 
about four-fifths of the titles being German, 
and a large share of the remainder French. 
The reviewer has been interested in tabulat- 
ing the results of an examination of sample 
pages, scattered uniformly through the book. 
From this it appears that nearly five thousand 
of the dissertations are from German univer- 
sities, slightly more than a thousand from 
French, and perhaps seven hundred and fifty 
from the Swiss, schools. Of the German univer- 
sities, Erlangen, Berlin, Gottingen and Leipzig 
stand first, each furnishing about five hundred 
titles, while Freiburg and Heidelberg stand 
considerably lower, and are not very closely 
followed by Rostock, Tubingen, Jena and 
Wurzburg. Of the Swiss universities, Zurich 
furnishes about as many titles as Rostock, and 
Berne as many as Jena. More than half the 
French dissertations are from l’Heole de phar- 
macie de Montpellier, most of the remainder 
being from Paris and from I’Eeole de phar- 
macie de Paris, those from the latter being 
rather more in number than from the former. 
One hundred and thirteen titles are in Russian, 
and perhaps nearly as many more are from the 
University of Dorpat. 
This glance reveals to us the position which 
Germany occupies in the teaching of chemistry, 
and, if the dissertations of the last few years 
alone were considered, it would be found that 
France stands much lower than is shown by 
the figures above. 
Dr. Bolton will receive the thanks, especially 
of all chemists who are engaged in research, 
for this addition to his many valuable contri- 
butions to bibliography, for it affords access to 
a very important field of chemical literature, 
which, for want of an index, has hitherto been 
practically closed. The original dissertation is 
often of far more value to the investigator than 
the re-edited work which appears in the jour- 
nals. The value of this book is still further 
increased by reference to those dissertations 
which are in the libraries of the Geological 
Survey and of the Smithsonian Institution ; 
and also—this would certainly be missing in no 
book of Dr. Bolton’s—by a very complete 
index, which fills ninety double-column pages. 
While this volume completes the undertaking 
