THE PRESIDENT'S ADDRESS. 53 



extent. It is a highly interesting fact that rudimentary organs 

 are almost always larger in the embryo than in the adult. This 

 brings me to another great argument in favour of evolution, viz., 

 the disclosures of embryology, which have led to the enunciation 

 by Fritz Muller and Ha3ckel of the law that " the ontogeny com- 

 prises the phylogeny," or in more ordinary language, that the 

 development of an individual is a sort of record of the development 

 of the species to which it belongs. This explains numerous cases 

 which are incomprehensible, except on the supposition of a common 

 descent, and appeals strongly to the mind. It has always seemed 

 to me that the most remarkable instance is the well-known one, that 

 the Xudibranch Mollusca, which have not any shell when adult, yet 

 possess a well-developed shell like a periwinkle when in their 

 embryo condition, although they are then within a membrane and 

 the shell is useless to them. There are, however, hundreds of 

 other instances. Thus the embryo grubs of Muscidce (Dipterd) 

 possess a head with antennas and jaws, although these organs 

 are absent in the hatched larvae. In the embryo larvae of Sphinx 

 there are ten pairs of abdominal legs, five pairs of which disappear 

 before hatching. The grubs of bees in the embryo condition have 

 a head like other Ht/menoptera, and three pairs of legs, but they 

 similarly disappear. The larva of C/uerocampa porcellus is remark- 

 able among those of Sphingidte for the absence of the dorsal horn, 

 but it exists in the very young specimens, but does not grow or 

 persist. The Acaruut are specially distinguished by the unseg- 

 mented abdomen, but it is segmented in many of the young larvaa. 

 The young of the tapir and wild-hog are striped, while the adults 

 are plain (other allied forms being striped), and the whelps of the 

 lion and the puma are often more or less striped like so many other 

 cats. The whale-bone whale has teeth in the fcetal, but not in the 

 adult condition, and the teeth in the front part of the jaw of the 

 calf and some other ruminating quadrupeds never cut the gum. 

 The young blackbird is spotted something like the thrush ; so are 

 the young of the common (white) gull. The tadpole of the common 

 salamander has gills, and lives in water ; Salamandra atra lives 

 high up in the mountains, and brings forth its young fully-formed. 

 This animal never lives in water in any stage, but if a gravid 

 female be opened tadpoles with beautifully feathered gills will be 

 found, which can swim when placed in water ; and there are hun- 

 dreds of other cases. I will just mention the singular life-history 



