1898] A THEORY OF RETROGRESSION 405 
reproduced exactly in the ontogeny, and then the latter would be as 
elaborate, and almost as lengthy as regards time, as the former. 
Moreover, the prototypes of the phylogeny could not exist in the 
enormously changed environment of the ontogeny. How, for in- 
stance, could a gill-breathing animal, or any of the higher forms 
which intervene between them and man, exist in the uterus, in 
which alone can exist those dim representations of the phylogeny 
that constitute man’s ontogeny ? 
It is this great change of environment, this close protection of 
the individual in the uterus and afterwards, which has rendered 
possible the evolution of man and the other higher animals. Oppor- 
tunity has thus been afforded for retrogression to plane away in- 
numerable characters which had become useless. The ontogeny has 
thereby been straightened, shortened, and simplified, and the evolu- 
tion of new characters, useful in the new environment, has become 
possible. Thus, for instance, have been rendered possible the higher 
characters of man, for even after birth he is closely protected, and, 
therefore, even in that portion of the ontogeny which intervenes 
between the infant and the adult has there been much retrogression. 
Consider how feeble and helpless is the infant after birth; but its 
prototypes of the phylogeny fought for their own existences. The 
infant can digest scarcely anything but milk, and its jaws are very 
feeble. Its prototype must have had much wider powers of digestion. 
Perhaps more remarkable than anything else is the retrogression of 
instinct in man. I have dealt at length with this question else- 
where, and have not space for it here; but consider how helpless 
is the infant at birth, how extremely incapable, as compared to 
young insects, for instance, of adapting itself, of its own initiative, to 
the environment. Later on it acquires all kinds of knowledge and 
ways of thinking and acting, which serve as a superior substitute 
for instinct. But meanwhile the mother’s protection, which has 
rendered possible this acquirement, has rendered useless also the 
instincts of its prototypes, which have therefore lapsed. Hence the 
retrogression of instinct in man. By it his mental ontogeny is 
shortened and simplified, just as by the retrogression of bodily parts 
his physical ontogeny is shortened. 
In the foregoing I have spoken of characters lapsing in orderly 
succession, the last first, the earlier later. But it seems to me 
probable that earlier characters may sometimes lapse before the 
later. This may happen when some parts of the phylogeny, and 
consequently of the ontogeny, are not direct, but form a loop, so to 
speak. The omission of the loop would straighten, and therefore 
shorten, the ontogeny, and considering how condensed is the latter, 
I believe this must often occur. G. ARCHDALL REID. 
9 VicroriIA Roap SoutH, SouTHSEA, 
