20 Compound Organisms and their Lessons . [January, 
itself both by eggs and buds. If one of these beings is cut 
into two or more pieces, each part lives and increases as if 
it had been a primarily independent organism. Sometimes 
also they are known to split up spontaneously, each portion 
starting in life independently, like the halves of a Protozoon 
which has divided itself. What is still more curious, if two 
Spongillse are placed close together they sometimes merge 
into one individual. Here, then, we have beings where it is 
impossible to decide by inspection whether any one of them 
is the produce, and the whole produce, of a single egg or 
not. Such a Spongilla may have divided itself, and one of 
these divisions may have coalesced with another Spongilla , 
which may be the entire product of a distinct egg or only a 
part of such product. 
Or we may take that fresh-water polype known as the 
Hydra, which has long been known from the faCl that it 
cannot be killed by mechanical division. Let it be cut 
transversely, or longitudinally, or obliquely into two parts^ 
or into more, each section becomes an independent Hydra. 
Naturally it throws out, at its sides, buds, which like itself 
are each provided with tentacles and with a mouth for cap- 
turing and absorbing food. Each such bud grows, and ulti- 
mately is detached as a distinct animal. Often before being 
thus thrown off it puts forth buds, and thus it may be said 
to exercise all the normal functions of animal existence 
whilst still united with its parent. At the same time the 
Hydra is capable of reproducing itself sexually by eggs. 
Consequently when we find one of these little beings .we 
cannot ascertain whether it has sprung from an egg or from 
a bud. In the former case it is, according to established 
views, a distinct animal. In the latter it is only a piece or 
fragment of an animal, forming a whole along with some 
other portions not to be identified, if still existing. Yet by 
no consideration, morphological or physiological, can the 
one, as it falls into our hands, be distinguished from the 
other. Each grows, captures and assimilates food, and re- 
produces itself both by eggs and by buds, precisely as does 
the other. The individuality and personality of these little 
beings must evidently be highly complex and perplexing. 
Up to a certain date the specimens formed by budding have 
been one with their parent and with each other. 
Another somewhat different type of compound or colonial 
existence is shown in the Flustra, or sea-mat, an animal 
often mistaken for a sea-weed. On each side of every “leaf,” 
as it is commonly called, we find a multitude of zooids, each 
inhabiting a little cell and leading an apparently independent 
