ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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different effects on the two parts of tlio cell. Reacting on one another, 
owing to their very distinct functional attractiveness for one another, 
the two parts have different duties in the individual life of the cell. A 
close “ mutualisme ” is established between the different regions of the 
cell, each of which is the seat of numerous diverse activities. 
The life of the physiological unit — call it energid, tentorium, or 
cell — is not the result of a function which owes its origin to the com- 
bined work of its different parts ; it is the consequence of the regular 
combination of a large number of very dissimilar activities which arise 
in various organs, and which converge towards one resultant, while 
preserving their own existence and value. 
Just as the physiology of the higher animals has succeeded in break- 
ing up the life of an organism into a series of more or less special 
functions, some of which may cease for the moment without bringing 
about the definite ruin of the whole, so cellular physiology has succeeded 
in showing that the same is true of the primordial organism. The final 
conclusion of the author’s work is that the life of the nucleus is essen- 
tially different from that of the protoplasm. 
The cell is exceedingly complex ; we must not forget that we know 
only some lines of its history ; the new conception of its physiology is 
unknown to all but students of cytology ; it would be well for physiology 
and general pathology if it were more widely known. 
y. General. 
Genetic Relations of Metazoa.* — Mr. W. Schimkewitch is of opinion 
that the Metazoa derived from the hypothetical Trochozoon passed through 
a stage which may be called that of the Enterocoelula, in which there 
was a pair of coelomic sacs. In the next stage this coelom divided into 
two parts, the coelom of the cephalic trunk and tentacles and the coelom 
of the trunk ; this may be called the Tentaculiger-stage. The Bryozoa, 
the Phoronidae, the Sipunculidae (?) and the Echinozoa are arrested at this 
stage ; in the first three the metanephridial system is developed in the 
hinder part, and in the last in the anterior part of the body-cavity. In 
the Chaetognatha and Brachiopoda (?) the hinder part of the body-cavity 
is divided into two, and, in consequence, the number of metanephridial 
tubes is increased to two pairs ; the Chaetognatha have lost the 
tentacles. 
In the Enteropneusta the anterior part of the coelom is divided into 
two portions, the anterior of which corresponds to the cephalic lobe, 
while the posterior is prolonged into the tentacles. These last are 
retained by Cephalodiscus , but lost in the polybranchiate Enteropneusta 
( Balanoglossus and Saccoglossus ). In the Acrania we may see the part 
homologous with the anterior section of the body-cavity of the Tentacu- 
liger-stage ; the hinder part is divided into a series of segments, and 
the metanephridial system is developed in the hinder part. The 
relationships of the groups are indicated by a table, in which the Ten- 
taculiger-stage is above the Enterocoelula ; to the right branches off the 
Notoneura Chordata, and to the left the Triarticulata (Brachiopoda and 
Chaetognatha) and the Tentaculata (Rhabdopleuridae, Bryozoa, Phoronida, 
Sipunculida, and Echinozoa). 
* Congr. Intern. Zoologie, ii. 2 (1893) pp. 215-40. 
