1090 Growth, its Conditions and Variations, [Novembe, 
At the same time the profuse existence of wandering cells isa 
necessary preliminary condition to reproduction. These cells, as 
the writer has already advanced in a former treatise, conjoin and — 
subdivide until from the union of cells, each of which possesses the 
structural peculiarities of only a minor portion of the organism, — 
are produced cells containing the structural characteristics of the — 
whole organism, and consequently suited to become the germs of | 
new organisms. | 
Such is presumably the general character of animal life opera 
tions. The food-getting powers of Protozoa are very slight 
Their cilia are inefficient organs, and only suited to the capture 
of very minute prey. As they increase in size their power of 
obtaining sufficient nutriment decreases. Hence division takes 
place and the offspring become wandering cells, since their 
chances in the life struggle are thus improved. With higher 
animals special conditions have rendered the colonial aggregation 
of cells advantageous, and cell-coherence becomes the rule. By : 
combined effort each cell succeeds in obtaining more food than it 
could have done by its unaided efforts. But in every case as the | 
size of the individual animal increases, its ability to satisfactorily 
supply all its hungry cells with food diminishes. The point x 
which the limit in this direction will be reached depends on the 
degree of efficiency in the food-taking organs, and also pen ihe 
quantity of available food, more nutriment being requisite ie 
greater the bulk of the animal. The 
When this limit is reached, individual life growth ceases. $ 
organic powers remain stationary for a time and then deterom 
tion sets in. This deterioration is apparently a necessary © jal 
in all organisms, arising from a gradual failure of the : ger 
life powers, or from inimical organic processes which e 
arise. Thar this is really the case, however, is not sure. Itis g 
means certain that an indefinite continuance of individual an! n 
life might not be possible if the reproductive process "a : 
pletely checked. It might reasonably be conjectured that toi” 
were possible it would have occurred somewhere 1m ee 
range of animal development, during which such an € a 
diversity of form and condition was produced. But such on 
of animals would certainly be at a disadvantage in the E 
gle, Its powers of continuous life must gradually suce? 
‘ ICAN NATURALIST, June, July, August, 1882. 
