1895.] The Distineticn Between Animals and Plants. 963 
In attempting to distinguish animals and plants by means 
of definite characters, there is another point that needs atten- 
tion. Primary characters are to be drawn from the mature 
condition of the organism, and not from the reproductive or 
the immature state. This is such an obvious proposition in 
the ordinary classification of animals or plants, that it seems 
strange that in diagnosing the two kingdoms it should have 
been entirely overlooked. There areremarkable similarities in 
methods of reproduction among plants and animals, not only 
in the processes, but in the external means for protection and 
in the methods of dissemination of the reproductive bodies. 
Especially is this true of non-sexual reproduction among the 
lower orders. The reproductive structures are sometimes very 
elaborate, and the organism in that state often attracts more 
attention than in the vegetative condition, as in the case of the 
Myxogastres. It is obvious that the individual is the object 
that we are studying and classifying, and therefore the most 
fundamental of characters should apply to the individual—the 
vegetative organism, and not to the mode by which a suc- 
cession of individuals is maintained. 
The following definition of plants and animals is suggested 
as meeting the requirements of the conditions of classification 
mentioned above : 
PLANTS are organisms possessing (in their vegetative state) a 
cellulose investment. 
ANIMALS are organisms possessing (in their vegetative state) 
a proteid investment, either potential or actual. 
The organism may be a cellular body with the investment 
extending to each protoplasmic unit, as is usual in plants, or 
it may be a ccenocytic body with the investment extending 
only to the compound units, as in most animals and in some 
plants (e. g., Mucorine, Siphonacex). As a rule, the investment 
is most prominently developed upon the general outer surface 
of the organism. 
By designating the constitution of the walls, it is intended 
to cover only the original or basic substance of which they are 
composed, and has no reference to subsequent depositions or 
infiltrations, of whatever character they may be. Thus in the 
