486 
NATURE 
[Marcu 21, 1907 
symmetry. This advance has not been without 
marked influence on the methods of determining the 
physical properties of crystals, The old idea to con- 
sider a crystal as a solid bounded by plane faces, the 
relative positions of which harmonised with Hatiy’s 
law of rational intercepts, is giving way to the more 
logical principle that a crystal consists of a homo- 
geneous arrangement of discrete particles in space. 
Indeed, as has been frequently pointed out, a theory 
which ignores the internal structure cannot avoid the 
difficulty presented by a peculiar case of pseudo- 
trigonal symmetry. To the new school, which is 
typified most completely by Schénflies’s well-known 
treatise, the present work belongs. 
Dr. Sommerfeldt devotes a considerable portion of 
his book to the determination of the thirty-two classes 
of crystal symmetry. He establishes the four possible 
types of axes of symmetry in the usual way, and 
proceeds to evolve the classes in the following 
order:—the holohedral groups; the merohedral 
groups, comprising those possessing centres of in- 
version, those without such centres, but having 
mirror-image symmetry; and, lastly, those without 
such centres, and enantiomorphous. In the discussion 
a modification of the ‘‘ Fundamentalbereich’’ of 
Schonflies is introduced. . It is the smallest spherical 
triangle defined by the elements of symmetry. The 
symmetry pertaining to each class and the shape of 
typical simple forms are clearly illustrated by means 
of the admirable plates, of which there is one for 
each class except that devoid of symmetry. After a 
brief discussion of the zonal law and the linear and 
‘stereographic projections, the author proceeds to 
what he considers not the least interesting portion 
of the book, namely, the application of the methods 
of vector analysis to crystallography. This form of 
mathematical analysis is undoubtedly graced by 
elegance, and presents the generalised formulz in neat 
guise, but its unfamiliarity to the ordinary student 
of crystallography seriously militates against the 
general utility of the book. The formulz in question 
—some of which, by the way, do not lend themselves 
readily to arithmetical computation, and are, there- 
fore, not of immediate practical use—could be estab- 
lished without greater difficulty by means of ordinary 
analytical geometry. Nevertheless, to the advanced 
student who may be versed in mathematics it would 
be interesting and stimulating to study a different 
method. The book concludes with a very ccmplete 
bibliography and a good index. 
Untersuchungen iiber ktinstlichen Parthenogenese 
und das Wesen des Befruchtungsvorgangs. By 
Prof. Jacques Loeb. German edition, issued with 
the author’s cooperation, by Prof. E. Schwalbe. 
Pp. viiit532. (Leipzig: J. A. Barth, 1906.) Price 
7.50 marks. 
‘THE greater part of this remarkable book appeared 
in English dress in the Decennial Publications of the 
University of Chicago, and has been already noticed 
in our columns. As is well known, Prof. Loeb set 
himself some years ago the task of discovering 
chemical or physical methods of stimulating de- 
velopment in unfertilised eggs. Taking every pre- 
caution which he could conceive of, he has been able 
to induce artificial parthenogenesis in the ova of sea- 
urchins, of the annelid Chaetopterus, and of the 
gasteropod Lottia gigantea. He thinks that the 
list will be added to as our mastery of the technique 
increases, for he does not believe that there is any 
essential peculiarity in those ova which develop in 
response to the artificial stimulation. As to the 
nature of the stimulation, Loeb is more and more 
convinced that it depends on setting-up or increasing 
WO. I951, VOL. 75! 
oxidation processes in the ovum, and also on the 
synthesis of nuclein substances from the protoplasmic 
materials. It is possible, he says, that the two pro- 
cesses are interdependent, and that, oxidative syn- 
theses take place. Everyone will wish more power to 
this ingenious experimenter’s elbow in his untiring 
efforts to gain control of life. 
Handbook of Metallurgy. By 
Translated by Henry Louis. Vol. ii. Second 
edition. Pp. xvi+867; illustrated. (London: Mac- 
millan and Co., Ltd., 1907.) Price 21s. net. 
Pror. Louis is to be congratulated on the comple- 
tion of the translation of the second edition of Dr. 
Schnabel’s great work. Little delay has been ex- 
perienced in placing it in the hands of English 
metallurgists, as the corresponding German edition 
was not published until 1904. The volume which has 
just been issued contains the metallurgy of zinc, and 
shorter sections on cadmium, mercury, bismuth, tin, 
antimony, arsenic, nickel, cobalt, platinum, and 
aluminium. As the first edition appeared nine years 
ago, there have been great advances in the metallurgy 
of some of these metals since it was written, and 
these have caused many alterations and a consider- 
able enlargement in the present volume. The 
changes are distributed throughout, the whole text 
having been carefully revised, but some of the most 
striking changes occur in the sections devoted to the 
production of aluminium on a large scale and to the 
electrolytic treatment of zinc. Electrolytic methods 
generally are fully treated, the author expressing his 
indebtedness to the works of Dr. Borchers for much 
of this part of the book. 
There is little to be said in criticism of Dr. 
Schnabel’s book. The description of alloys is usually 
rather meagre, with curiously slight regard to the 
work of the last twenty years. Then, again, the 
rapidity with which the Silesian zinc furnace is giving 
place to the Belgo-Silesian furnace does not seem to 
be realised by the author. In general, however, the 
information is full, accurate, and up to date, and is 
conveyed in a pleasant, readable manner. 
Dr. Carl Schnabel. 
LETTERS TO THE EDITOR: 
[The Editor does not hold himself responsible for opinions 
expressed by his correspondents. Neither can he undertake 
to return, or to correspond with the writers of, rejected 
manuscripts intended for this or any other part of NATURE. 
No nolice is taken of anonymous communications.] 
The Inoculation Accident at Mulkowal. 
T stouLp like to direct the attention of your readers to 
this matter. The evidence regarding the unfortunate 
Mulkowal accident, as given in the Lancet and the British 
Medical Journal for February 2, and in the Journal of 
Tropical Medicine for February 1, shows that on October 
30, 1902, nineteen persons were inoculated from a single 
bottle of Haffkine’s prophylactic labelled 53, while 
numerous other persons were inoculated from other bottles. 
A weck Jater all the nineteen inoculated from bottle 53N 
developed tetanus, and subsequently died, while none of 
the others suffered at all. This gives a strong argument 
in favour of the view that the poison was associated with 
the contents of that particular bottle; but the evidence 
is clearly not mathematically absolute even on this point, 
while it gives no indication whatever as to when the 
tetanus bacillus entered the bottle. It might possibly have 
entered during the processes of manufacture and bottling, 
or iater through a loosened cork, or in several ways during 
the opening of the bottle and the inoculation of the con- 
tents. But the commission that was appointed to consider 
the subject seems to have somewhat hurriedly adopted the 
conclusion that it actually entered during preparation, and 
not later. Mr. Haffkine, as head of the laboratory, was 
