1904 | CURRENT LITERATURE 151 
The work bids fair to be a most satisfactory one. A similar work for North 
America is greatly to be desired, for Lesquereux and James’s Mosses of 
North America is now twenty years old.—C. R. B 
The problems of life. 
THIS BOOK? contains a theory of ontogenic development, or rather an 
exposition of the fundamental principle governing ontogenic phenomena. To 
use an illustration of the author: if one wished to study the flow of rivers, 
and to determine in advance the course of a river in all its details, it would 
be necessary to know the rapidity and density of the water, the inclination 
and geological structure of the bed and banks at all points of its course, 
resistance of materials composing these, etc., so that the solution becomes 
practically impossible in detail. But theoretically the fundamental principle 
involved is simply that of gravitation. It is the same with the problem of 
development. Knowledge of all the various secondary factors that compli- 
cate each case is not necessary; what is wanted is knowledge of the funda- 
mental principle governing all ontogenic phenomena. The author believes ~ 
he has found this in the principle of “développement monodique.” 
The principle of monodic development is derived from the author’s ideas 
of the nature of assimilation, growth, and of cell division, which are discussed 
in the first part of the work, and are outlined in a review of it in this 
journal.3 
The biomolecules of the egg assimilate the deutoplasm and so reproduce 
by division; this causes division of the biomores, and this cleavage (cell 
division). Thus assimilation is the first and necessary cause of each cleavage, 
and the assimilation is accompanied by progressive chemical ontogenic 
changes. The author here introduces as the main prop of the monodic theory 
the principle of ‘“heterogenetic” development, viz.: that, owing to the nature 
of “biomolecular development,’ two daughter-cells must be different in 
constitution both from one another and also from the mother-cell. This is 
established as a universal principle in development by the consideration that 
there are only two other possible modes of cell division, viz.: autogenetic, in 
which the daughter-cells are like each other and also like the mother-cell, 
and homogenetic, in which the daughter-cells are like each other but different 
from the mother-cell, and that these are excluded as possible modes of 
development, for the assumption of either of them as a mode of development 
leads to an absurdity. 
Thus it follows that the constitution of the cells alters with each cleavage 
which ex hyf. is preceded by a period of assimilation. 
The next step in the hypothesis leads to the principle of monodic develop- 
2 GIGLIO-Tos, ERMANO, Les problémes de la vie. II* partie; |l’ontogénése et ses 
problémes. 8vo. pp. 368. Cagliari, chez l’Auteur, a l’Université, 1903. 
3 Bot. GAZ. 31:275. Ig0l. 
