282 THE ZOOLOGIST. 
I need not tell you how this has happened; how Charles 
Darwin “ found a great truth trodden under foot .. . and ridiculed 
by all the world” (Huxley); but I may, perhaps, remind you that 
the outcome of the ‘ Origin of Species’ was the conviction that, in 
Zoology, truth is only to be found when the doctrine of the blood- 
relationship of Animals is steadfastly borne in mind. And I hope 
to show you that this animating principle has not only excited 
investigators, but linked their results into coherence, if not into 
truth. Ido not propose to weary you by taking you into details 
which are of interest only to the worker in a special field; I shall 
speak only of such discoveries, and of their apparently logical 
results, as will, I hope, prove to be of interest to zoologists 
generally. 
And, firstly, as to the broadest classification of the Animal 
Kingdom; that which we are in the habit of using is the 
Lamarckian grouping of Vertebrata and Invertebrata; but it is 
one which to-day no competent zoologist would ever dream of 
teaching! I do not doubt that it will be continued to be used by 
Man, as a mark of the distinction between Man and his zoological 
allies, on the one hand, and “the rest” on the other. But it is, 
nevertheless, one which denies or neglects the greatest results of 
modern inquiry. It is one which expresses the beliefs of just 
half-a-century ago; for it was in 1835 that that great anatomist 
and physiologist, Johannes Miiller, quoted with approval the 
words of Kant, ‘‘ The cause of the particular mode of existence of 
a living body resides in the whole”; but it neglects a doctrine 
which is nearly fifty years old, too,—the doctrine of the great 
Belgian biologist, Theodor Schwann, that animal cells are inde- 
pendent in their mode of growth. This doctrine of Schwann’s 
made steady progress, and the cellular composition of the higher 
animals was, long since, unreservedly accepted. 
But the teachings of anatomists and microscopists remain 
limited to a narrow circle until they are used for the purposes of 
systematic classification, and it was not till 1866 that the logical 
result of our knowledge that some animals and some plants are 
composed of a number of cells which are united in a common 
organism, and subserve its different functions, led Prof. Haeckel 
to institute a third division of the Kingdom of Animated Nature, 
and to speak of Animals, Plants, and Protista, or first organisms, 
neither truly animal or vegetable. 
