242 
NATURE 
[JANUARY 14, 1904 
apparently under the influence of gravity, so as to take 
up the same configuration as before. This fact is 
highly significant in connection with the production 
of perfect and normal embryos, although the positions 
of the earlier formed blastomeres may have been so 
artificially shifted that their cell descendants occupy 
abnormal positions in the otherwise normal larva. 
The correctness of this general interpretation is also 
supported by the readiness with which partially 
separated blastomeres will form double embryos. 
The two masses of nearly isolated cytoplasm thus 
develop independently, the lack of adequate contact 
or continuity between the corresponding parts of the 
two cells being apparently responsible for the mon- 
strosity. An instructive comparison is afforded by a 
consideration of the results of artificially induced 
union of originally separate blastomeres of similar 
order. If these are approximated so that the axes of 
the different substances in each are parallel, they 
segment as one organism, that is, the cell division 
is coordinated. If, however, the axes are divergent, 
then each blastomere continues to segment more or less 
independently, and monsters of various degrees result. 
satisfactory explanation of the phenomena of develop-_ 
ment and regeneration. At present it is sufficient to 
analyse and investigate experimentally the agencies 
that are concerned in these and other vital processes; 
we shall thus, and only thus, be able to elevate the 
surviving elements of existing hypotheses to the rank 
of well-founded theory. 
The volume by Dr. Maas will form a useful source 
of information for those who may desire to know what 
is being done in these directions. Its author does not 
claim to have treated the subject exhaustively, and, 
indeed, we could wish the sections dealing with the 
chemical and physical aspects of the matter had been 
expanded. Nor will the reader who is familiar with 
the work of Driesch, Roux and others perhaps find 
much recorded that will be new to him, but the present- 
ation of the subject-matter is, on the whole, judicious 
and critical. The work covers a wider range than 
might be gathered from the general tenor of the pre- 
sent article, but as the whole subject deserves more 
| general attention than it receives, it appeared to be 
These embryos, arising from isolated blastomeres | 
of the first or following cell-generations, and also those | 
originating from the fusion of previously isolated ones, 
concur in one remarkable characteristic, viz. the size 
of the larva at any given stage is proportionate to the | ~ 
relation between the cell from which the embryo 
actually arose, and the ovum of the species. Thus 
embryos from either of the first two blastomeres are 
half the normal size, and so on. 
This variation in size is effected by a corresponding | 
reduction in the number of cells that go to make up 
the different parts or regions of the whole, and not 
by a difference in their size. At first sight this cireum- 
stance might seem to favour the hypothesis of 
“unequal ’? nuclear divisions, i.e. the production of 
daughter cells with constantly segregating potenti- 
alities. But any such explanation is at variance both 
with the facts of development, taken as a whole, and 
with those of regeneration as well. What the evidence 
does seem to point to is the existence of definite sub- 
stances present in the cytoplasm, and that these, 
though not actually representing the several organs 
in parvo, nevertheless do represent substances necessary 
to the formation of these organs—a very different thing. 
It is, then, intelligible why an organism that is left 
with only half the amount of any one such substance 
can only produce half the number of cells during 
cleavage; and a working hypothesis can be formed 
as to why regeneration is possible in some cases 
whilst it is apparently excluded in others. There 
exist strong grounds for believing that the formative 
stimuli leading to organogenetic development normally 
reside in the nucleus, but unless the substances cap- 
able of responding or of cooperating in the response 
to a stimulus are present, a normal result need no more 
be expected than that a printing machine should be 
capable of turning out a printed page unless the type 
had been inked. 
But though the ground is being broken, much will 
have to be done before we are in a position to give a 
NO. 1785, VOL. 69] 
more useful to attempt to indicate some of the actual 
results and the questions arising from them, than 
merely to give a discursive synopsis of a book that 
should be read by all who are interested in the more 
important biological problems of the present day. 
J. Bags 
THE ALKALI AND CHLORINE INDUSTRY. 
La Grande Industrie Chimique Minerale. By E. Sorel, 
Ancien Ingénieur des Manufactures de l’Etat. Pp. 
79. (Paris: C. Naud, 1904.) Price 15 francs. 
Stee work is concerned with the alkali industry and 
with those manufactures which naturally group 
themselves around it. That is to say, it treats of soda 
and potash, the chief salts of sodium and potassium, 
the halogens, and the principal industrial compounds 
of the latter, such as bleaching-powder and _ the 
chlorates. 
The point of view adopted is essentially that of the 
manufacturing chemist or chemical engineer. 
Generally, however, the treatment is rather broader 
than this might indicate. Thus the history of a process 
or the growth of an industry is often outlined, and the 
mode of occurrence of the raw materials used is de- 
scribed more or less fully. As further illustrating the 
same point we note that, in connection with hydro- 
chloric acid, several pages are devoted to a discussion 
of the effects which the acid vapours discharged from 
chemical works produce upon the vegetation of the 
locality. This, again, is followed by a chapter in which 
the general principles of the condensation of vapours 
are discussed from the thermodynamical standpoint. 
Nor does the author disdain to lighten his pages with 
occasional items of miscellaneous—not to say trivial— 
information. We learn, for instance, that in Central 
Africa ‘‘ les enfants courent aprés un morceau de sel, 
comme les nétres aprés un bon-bon.”’ 
The salt industry is dealt with in the opening 
chapter. There is a good description of the production 
of salt from sea-water, and some particulars of the salt 
deposits of Cordova, Lorraine, Stassftirt, and Transyl- 
