1893,] Recent Literature. 893 
the study with the microscope; the ninth of microphotography, and the 
tenth consists of a large bibliography of diatum literature. Of the gen- 
eral treatment of the subject there is much to be desired. The chapter 
on microphotography is clear, and will doubtless prove of value to 
students, but the rest of the work is rather antiquated. Thus, the chap- 
ter on the movement of diatoms is based upon an article dated 1866, 
and is without a single reference to the later literature, the observations 
of Pfitzer, Schilberszky, etc., being ignored. The bibliography appears 
to be fairly complete, but the proof-reading of this portion is very bad. 
The typographical appearance of the book is good, but the publishers 
have committed the not unusual fault of putting it upon much too 
heavy paper. 
Kennel’s Zoology.'—In the past three or four years we have 
noticed not a few German text-books covering a greater or smaller por- 
tion of the field of zoology. This is the latest to appear on our table. 
In most respeets it pleases us, in others it does not. Its author is at 
once too radical and too conservative. Thus he has completely done 
away with the old group of worms; he denies the validity of the group 
of Arthropods, and has assigned Amphioxus to the group of Tunicates, 
the latter group, in his linear arrangement, being sandwiched between 
the Brachiopods and Molluscs. To descend to details: The work is 
divided into two parts—general and special zoology. In the first we 
have, at the beginning, a discourse on what is a species followed by a 
brief account of evolution, and this in turn by the usual definitions of 
organic and inorganic, animals and plants, individuals, ete. Then fol- 
lows the cell, protozoa, tissues and organs. In the special part we find 
the systematic zoology of the Metazoa Bs: meis: Sete As 
already hinted, the old group of d the A rthro- 
pods are given short shrift with a few words like the Biain: “The 
Tracheata, which have previously been regarded as a sub-group of the 
class of Arthropoda, equivalent to the Crustacea, have, as it appears, 
aside from a series of external resemblances of form and extremities, no 
nearer relationships to the crabs.” The failure to recognize the Chor- 
dates as a valid division seems also a questionable procedure. The 310 
figures which illustrate the work have been mostly drawn by the 
author, either from nature or with the use of pre-existing figures, and 
are largely reproduced by some of the mechanical processes. Many of 
the ms are very instructive. Press-work and paper are good, as 
we always find them in German text-books. . 
5 Lehrbuch im emos von Dr. Julius Kennel. Stuttgart, Ferdinand Enke, 1893, 
$8vo, pp. xvi x 
