666 THE AMERICAN NATURALIST. | [Vor. XXXVI. 
that enzymes have been the subject of considerable careful investi- 
gation during the past fifteen years and that their nucleoproteid 
nature which he has just * discovered " is now in fact being given 
up by the men who are most prominent in the chemistry of the 
enzymes. Only a few months ago Pekelharing prepared a pepsin 
which contained no phosphorus ; this pepsin still contained a minute 
trace of iron, as shown by qualitative tests, but it was too small to be 
determined quantitatively and Pekelharing paid no further attention 
to it. There is no reason for supposing that Pekelharing could not 
purify this pepsin still further and thus get rid of the last traces of 
iron, as he has already removed the last traces of phosphorus, should 
there be any sufficient object in his doing so. 
Since the only experimental evidence cited by the author is thus 
meaningless there is scarcely any point in following him in a review 
of this kind through other subjects, such as synthesis of living matter, 
growth, cell division, reproduction, muscle contraction, the activity 
of the sense organs, and the chemical processes of the central ner- 
vous system. The discussions seem all like the products of a wan- 
dering mind whose scientific bearings have been completely lost. 
It seems surprising that a firm like that of Gustav Fischer at 
Jena could have been induced to publish a work of this kind. 
A New Laboratory Manual of Biology. — The teacher of biology 
is confronted not only with the problems of his own science, but with 
those of how best to teach it, and a laboratory manual is a provi 
sional answer to many questions of the second kind. From this 
standpoint Hargitt's! Outines will be of much service to teachers. 
It abandons the older method of beginning with the simplest repre- 
sentatives of animals and plants which are at the same time least 
familiar and most difficult of study, and adopts the more recent 
practice of introducing the subject by well-known types, in this 
instance the frog and the fern. "Then follow exercises on the animal 
and the vegetable cell, and finally a series of type animals and plants 
ranging from hydra and the molds to the grasshopper and flowering 
plants. The mingling of plants and animals in the latter part of the 
work, though a time-honored practice, destroys the unity which the 
plant and the animal kingdom ought to show and substitutes nothing 
of special value for it. The text, which is for the most part clear, 1S 
1 Hargitt, C. W. Outlines of General Biology. C. W. Bardeen, Syracuse 
N.Y. 164 pp. 
