95 
NATISLRE. 
| NOVEMBER 29, 1906 
land circle diagram, and emphasis is laid on the 
necessity for proper phase relations being maintained 
between the applied voltages. A short chapter is 
devoted to induction meters, the principles of which 
are explained analytically and graphically. 
Compound alternators are referred to somewhat 
scantily, only two types being described, both of 
which are manufactured by the Westinghouse Com- 
pany. The parallel running of alternators is 
examined by the aid of synchronous reactance, and 
various methods of synchronising such machines are 
described. 
The operation of synchronous motors is treated in 
the same way at considerable length, and an interest- 
ing graphical method is given for finding the value 
of the motor E.M.F. for any given load, due, we 
understand, to Mr. G. T. Bennett, of Emmanuel 
College, Cambridge. There is a short reference to 
the hunting of such motors, and to the action of the 
ainortisseur. The book concludes with a chapter on 
the rotary converter, with special patagraphs on the 
E.M.F. relations, current relations and ohmic loss, 
starting, pressure regulation, efficiency and hunting. 
It may be remarked that no mention whatever is 
made of transmission lines, a subject which would 
naturally be included in a book such as this; but 
possibly the author may have adequate reasons for 
the omission. 
Apart from criticism of the contents of the book, 
it is necessary to direct attention to one point 
referred to in the preface, viz. the question of 
references to previous writers whose works have been 
requisitioned. It is quite true that such references 
are not of great value to the student, and would be 
unnecessary for others if no original matter were 
tmtroduced. This, however, is not the case, and it 
is unreasonable to assume that the learned persons, 
mentioned by Mr. Lamb, who read the book will be 
acquainted with the authorship of this original 
matter. The number of engineers who are practi- 
cally familiar with all branches of alternating- 
current science must be very small, and anyone wish- 
ing to study a particular branch from Mr. Lamb’s 
book would naturally ascribe to him the credit for 
some of the original matter contained therein. In a 
few places, contributions have been abstracted from 
the proceedings of learned societies. without a word of 
acknowledgment. Rather than adopt such a course 
it would be better to adhere to the system in vogue in 
Germany, where a man who writes a book on any 
subject without supplying with it a complete biblio- 
graphy is considered a hopeless amateur. 
THE CELL AND HEREDITY. 
Die — stofflichen Grundlagen der Vererbung im 
organischen Reich, Versuch einer gemeinverstand- 
lichen Darstellung von Eduard Strasburger. Pp. 
vili+68. (Jena: Gustav Fischer, 1905.) Price 
2 marks. 
HIS little sketch of the cell as the bearer of the 
hereditary qualities of the organism is full of 
interest, like everything that springs from Prof. 
Strasburger’s pen. It is written in somewhat popular 
NOs Meas, WOle 75 | 
style, but is nevertheless a thoughtful and real con- 
tribution to the literature of the subject. 
The book opens with a brief but sufficient account 
of the processes associated with the formation of the 
sexual elements, and with the outlines of nuclear 
division in so far as they are necessary for the under- 
standing of the main problem. 
The author follows current opinion in laying great 
stress on the qualitatively equal division of the 
chromosome secured by the mode of longitudinal 
fission of the chromatic thread, and he regards the 
chromosomes themselves as permanent elements of 
the cell nucleus. He explains in detail what is meant 
by ‘‘reduction-divisions,’? whereby the number of 
chromosomes in the sexual cells becomes reduced to 
one-half that characteristic of the nuclei of the 
body cells of the animal or plant. This reduction is 
dependent on the circumstance that the paternal and 
maternal chromosomes, which at sexual fusion are 
contributed to the fertilised ovum, remain distinct in 
the nucleus of that and the succeeding cells which 
originate from it. But at some period in the life- 
cycle certain cells, all or some of the descendants of 
which are destined to give rise again to sexual 
elements, exhibit two well-marked nuclear divisions 
that follow rapidly upon each other. In this way a 
definite phase (termed by some writers the maiotic 
phase) is intercalated in the cellular life-cycle of the 
organism, and it marks the transition from the cells 
with ‘‘unreduced’’ to those in which the nuclei 
possess the ‘‘ reduced ’’ number of chromosomes: 
The essential feature connected with the maiotic 
phase lies in the manner in which the reduction in 
the number of the chromosomes is effected. Instead 
of a distribution to each nucleus of respective moieties 
of every chromosome taking place, as in the ordinary 
nuclear divisions, entire chromosomes first become 
temporarily united in pairs, and then the two members 
of each pair diverge from each other, and, aggre- 
gating into two groups, give rise to two nuclei each 
of which thus respectively contains half the whole 
complement of chromosomes present in the original 
nucleus. 
There is some divergence of opinion as to the exact 
method by which the association and subsequent dis- 
tribution of the chromosomes is effected during the 
maiotic phase, and perhaps it may vary somewhat in) 
different organisms, but there is a general agreement 
as to the final result. ; 
There exists a considerable weight of evidence. 
tending to prove that the different chromosomes are 
responsible for different characters or groups of 
characters in the organism as a whole, and _ this 
circumstance is to be correlated with the fact that an 
equal number of these bodies is normally furnished 
to the fertilised ovum by each parent. Each chromo-. 
some, therefore, which is derived from the one parent 
will have its homologue or duplicate originating from 
the other. The importance of this becomes manifest 
when the facts of reduction are considered in relation 
to the behaviour of hybrids or crosses, in which a 
given character or group of characters (allelomorphs 
of Bateson) differs in the two parents. When such 
