370 JOURNAL OF SCIENCE. 
stages of any other vertebrate animals, we shall find that they possess 
exactly the same gill-arches. But it is only in fishes that they retain 
their original form and develope into respiratory organs. In other 
vertebrates they seem to disappear, developing into other organs— 
being used partly in the formation of the jaws, and partly in that of 
the organ of hearing. Such structures are, probably, just as abun- 
dant in the vegetable as in the animal kingdom. There are among 
fruits and seeds many cases of what we term suppression, which 
illustrate this feature in development. The Coconut is a good 
example. If we cut a mature Coco-nut across, we find that there is 
only one cavity containing one seed. But at the base of the nut are 
three pits or depressions, which evidently must have some meaning. 
To find the whole clue we would require to see a flower in which this 
part, the ovary, was in a very immature condition, when we would 
find that its cavity was 3-celled, each cell containing a rudimentary 
seed. But in the process of ripening, two of these seeds and their 
cavities disappear and become absorbed, and the mature fruit appears 
to consist of one seed only. Now facts of this nature are very 
abundant, and they are most important in enabling us to understand 
something of the past history of plants, and hence to classify them 
accurately. In the case in point, the question of classification does 
not present many difficulties, but I will just point out how this case 
might be important. One of the most prominent characters of the 
class to which the Coco-nut belongs is that the parts of the flower 
are usually arranged in threes, there are, for instance, 3 or 6 perianth 
leaves, 3, 6, or 9 stamens, and usually 3 carpels. But if we were 
arguing from the structure of the mature fruit only, we might think 
we had to deal with a plant having 1 carpel only, and the question of 
classifying such a plant might present a serious difficulty. But the 
examination of the rudimentary fruit settles the question for us at 
onee, and we come to the very natural conclusion that the ancestral 
form of the Coco-nut adhered to the type from which its descendant 
had varied, and was furnished with a 3-celled fruit. 
I shall have occasion to refer to other cases later on—meanwhile 
I may just remark that the study of such structures, and indeed, of all 
the remarkable changes undergone by every living organism during 
its development from the first cell to the fully formed state, has led 
up to the theory expressed in the following brief statement, viz., that 
(Ontogenesis or) the development of each individual organism, is a 
short and quick repetition or recapitulation of (Phylogenesis or) the 
development of the tribe to which it belongs. In other words—we. 
see more or less perfectly in the development of each individual, the 
progressive stages of development through which all its ancestors 
have passed. 
5. The fifth point to which I now refer is, the Geographical — 
Distribution of animals and plants. This subject is one which hag 
only of late years received that amount of attention which its 
importance deserves. And the very value we attach to it now, and 
the immense amount of light it throws on this question of evolution 
illustrate as well as anything could do, the chilling effect exercised on 
Science by the old dogmatic teaching regarding Creation. As long 
as men believed that every animal or plant belonged to some 
particular species which—at some conveniently far-back period—had 
been created once and for all,—the problems of geographical dis- 
