290 Proceedings of the Eoycd Soeiety 
6. Further Chemical Considerations . — It is an observed fact tbat 
when amoeboid cells unite into a plasmodium, there takes place the 
most remarkable intensification of the activities of the mass. The 
compound amoeba seem possessed of all and more than all the 
activities of its component amoeba — pseudopodia of the most extra- 
ordinary length and size are thrown out, and motion is far more 
rapid ; in short, it would seem that not only are the activities of the 
component amoeba summed but multiplied. The coalescing amoebae 
may be regarded as serving as food to one another — their waste pro- 
ducts and their surplus water are squeezed out and got rid of, and 
thus we can readily understand the summation of their activities. 
But how is this apparent multiplication of activity to be explained ? 
We have seen how carbonate of ammonia, an oxidised body 
isomeric with urea, is exceedingly stimulating to protoplasm; and 
Mr Darwin’s researches have also shown that other alkaloids and 
waste products are excessively stimulating, and set up the most 
extraordinary aggregation ; and that a poison, for instance, may act 
by excessively exaggerating this normal process. Here then is a 
use, not merely for the protoplasm, but actually for the waste pro- 
ducts — the waste product of one cell acting as a stimulant w^hen it 
meets the protoplasm of another. And from this consideration 
again new series of speculative applications radiate off in all direc- 
tions. One may suggest that the use of the alkaloids in the coffee 
or strychnine or Calabar bean is not merely to protect the young 
embryo from being eaten by animals, but as a stimulant to germina 
tion. Or we may introduce the same conception into our specula- 
tions as to the uses of manures, in which the most valued consti- 
tuents are precisely those salts which, like carbonate of ammonia, 
produce great aggregation. 
Again, passing from the plasmodial union of cells to the probably 
derived union of ovum and spermatozoon, we cannot avoid imagining 
the latter bringing not merely a trifling contribution of additional 
protoplasm, but a store of substances especially stimulating to the 
vast mass of the ovum. And the identification above suggested 
of aggregation with the protoplasmic changes visible in the ovum 
after fertilisation, is thus seen to be by no means so improbable as 
might at first appear. 
7. Need of an Explanation of the Phenomena of Aggregation . — 
