862 
quire one already versed in the literature to 
extract the truth from the footnote revision. 
Even, however, if the student succeeds in this, 
he will soon be confused by the plain unre- 
vised statement on p. 106 that the course of 
cleavage is different in lamellibranchs and 
gastropods, whereas the recent work has 
demonstrated a fundamental similarity. It is 
also to be regretted that the editor should, ap- 
parently, have felt unable to replace some of 
the older figures with more accurate recent 
ones; not a single figure from the newer 
works is introduced. 
A feature of the revision that will be heartily 
welcomed is the appendices to the lists of litera- 
ture, in which the works published since 1893 
are included. An important omission from 
the usually full and accurate lists is that of 
Heath’s valuable paper on Ischnochiton, the 
more noticeable from the scantiness of the 
literature of the embryology of the Amphi- 
neura. 
Misprints are not common, but it is rather a 
serious one that credits Hatschek’s figures 
of the cleavage of Amphioxus given on p. 5387, 
to Salensky. The present writer finds his 
initials once F. K. and again F. H., which 
arouses the suspicion that others also may 
have ground for complaint. 
Take it all in all, the book is a good trans- 
lation of the standard work on the subject, and 
the revision will at least suffice to guide the 
serious student tothe more recent literature. 
195 JR, ID, 
The Play of Man. By KARL GRoos. Translated 
by ExizABETH L. BALDWIN, with a preface 
by J. MARK BALDWIN. New York, Appleton 
& Co, 1901. Pp, 412. Price, $1.50. 
This is not a drama, as the ambiguous title 
might signify, but a scientific treatise on sport 
and pastime, the performance of life’s activities 
not for serious purposes, but for the solitary or 
cooperative pleasure in them. The author in- 
cludes in his term the playful activity of the 
sensory apparatus in feeling, temperature, taste, 
smell, hearing and sight; the playful use of the 
motor apparatus, and the playful use of the 
higher mental powers. His second order of 
play is socionomic, that is, it takes two or more 
SCLENCE. 
[N. S. Von. XIII. No. 335. 
to fight, play chess, torment, haze, court, coop- 
erate in diversion. The facts and results of 
over play and diseased play are not neglected. 
Part III. is devoted to theoretical explana- 
tion of sport, the author finding its groundwork 
in the following: 
1. The discharge of superabundant vigor— 
the physiological cause. 
2. Activities of ancestors wrought in their 
children in the form of hereditary predisposi- 
tions—the biological cause. 
3. Pleasurableness and freedom from purpose 
—the psychological cause. 
4, The enjoyment of imitating what produces 
agreeable or intense feelings—the esthetic 
cause. 
5. The strengthening of the social tié—the 
sociological cause. 
The closing pages are devoted to the relation 
of play to pedagogics. We have only space to 
quote one sentence, ‘‘ At school one should 
learn to work, and he who does everything play- 
fully will always remain a child.’’ The reader 
will find throughout the work a becoming mod- 
esty in view of a new science, and a goodly por- 
tion of playfulness to relieve the monotony of 
dull classification. 
@, 40, Wil, 
Text-book of Inorganic Chemistry. By Victor 
von RicHTER. Edited by Prorrssor H. 
KLINGER, University of Konigsberg. Author- 
ized translation by EDGAR F. Smiru, Pro- 
fessor of Chemistry in the University of 
Pennsylvania, assisted by WALTER T. TaG- 
GART, Instiuctor in Chemistry, Fifth Amer- 
ican from the tenth German edition. Care- 
fully revised and corrected. With sixty-eight 
engravings on wood and colored lithographic 
plate of spectra. Philadelphia, P. Blakis- 
ton’s Sons & Co. 1900. Pp. 430. $1.75. 
The continued popularity of this book is 
shown by the frequent editions; in this edi- 
tion, notices on liquid air, the new gases in the 
atmosphere, and ten pages of physical chem- 
istry introduced into the chapter on metals, 
indicate careful revision, and a desire to bring 
the book up to date, without changing its gen- 
eral character. The characteristic of von 
Richter’s book is the great amount of condensed 
