472 LIFE-HISTORIES 
life.’ Its exact chemical constitution is not known, nor 
does it seem likely that it ever can be known; for to analyze a 
sample of protoplasm chemically is to kill it, and dead pro- 
toplasm surely differs in important ways from protoplasm 
alive. Moreover, through the many complicated reactions 
going on within, any active mass of protoplasm is doubtless 
continually changing its composition. One of the products 
of the activity of the protoplasm of a tint-ball is the blue 
substance above mentioned; another product is the chloro- 
phyll by means of which it is able to make food in the sun- 
light like any other plant containing leaf-green. Still another 
product is the gelatinous material forming the envelope by 
which the little mass of protoplasm is surrounded. Chemical 
tests would show that this envelope consists of a kind of 
cellulose. The food which the protoplasm is able to make 
from the substances it absorbs through its cellulose shell 
from the surrounding water, is used by the plant as material 
for growth. That is to say, it uses the food to make new 
protoplasm out of which come new coloring matters, new 
cellulose, and other organic products. As the growth of the 
sphere is mainly in one direction it becomes elongated into 
an ellipsoid as shown at B. Meanwhile, the denser central 
part of the protoplasm has similarly elongated and finally 
divided into distinct halves. These halves move toward 
the ends of the ellipsoid, thus becoming surrounded on all 
sides by the thinner protoplasm. Soon there appears in the 
ellipsoid a plane of separation extending through the center 
at right angles to the long axis; then each of the portions of 
protoplasm on either side of this plane becomes larger and 
rounder, and each along the plane of separation builds a 
layer of cellulose which presently appears as a cross parti- 
tion (C). At last, as a result of further growth and rounding 
we have two distinct spherules of protoplasm, each with 
its central, denser part and each surrounded by its own 
cellulose envelope essentially like the original tint-ball. Thus 
through growth and division one plant has become two. 
These plants may remain attached to one another and each. 
of them may divide again and repeat the process a number 
of times without separating. The result then is a colony in 
