Marcu 15, 1901.] 
The Penycuik Experiments. By J. C. EwART. 
London, A.and C. Black. 1899. Pp. xciii + 
177. 
Experimental Contributions to the Theory of 
Heredity. A. Telegony. By J. C. Ewart, 
Proc. Royal Soc., Vol. LXV. 1899. Pp. 
243-251. 
Guide to the Zebra Hybrids, etc., on Exhibition 
at the Royal Agricultural Society's Show, York. 
By J. C. Ewart. Edinburgh, T. and A. 
Constable. 1900. Pp. 51. 
About ten years ago there was an agitation 
in England for the establishment of an institu- 
tion to experimentally test current theories re- 
garding the processes of evolution. A memorial 
was circulated, and signed by many eminent 
persons, but the castle—or rather menagerie— 
in the air which enthusiasts had built did not 
descend to solid ground. In the meanwhile, 
however, certain individuals were laying plans 
of their own. Experiments in breeding moths 
had already yielded remarkable results. The 
experimental method had become fashionable, 
at least in theory, and it seemed that there were 
large possibilities before those who had time and 
money at theircommand. Under these circum- 
stances it was, perhaps, not remarkable that 
Professor Ewart, aided and abetted by various 
friends, should have undertaken to breed equine 
hybrids to prove the validity or otherwise of 
the theory of telegony. But if the Penycuik 
experiments were thus anatural product of the 
times, they were for that reason the more timely, 
and all biologists may be thankful to the Scottish 
professor for having planned them so carefully, 
and carried them out so satisfactorily. 
And now that we have the published results 
before us, what of telegony? The evidence on 
which it rested, at least so far as the Equidee 
are concerned, is so thoroughly disposed of 
that it seems almost superfluous to discuss it. 
Professor Ewart did not start out with the prop- 
osition that telegony was absurd, and the state- 
ment that he wouldsoprove. Onthe contrary, 
whatever he may have thought of the doctrine, 
he gave it every chance. He also got results 
similar to those which had been held to prove 
telegony. Mulatto, a West Highland pony, 
had a foal by Matopo, a Burchell’s zebra. Sub- 
sequently Mulatto had a second foal by Benaz- 
SCIENCE. 
423 
rek, a gray Arab. This foal, which, except 
telegony be true, had no zebra blood in its 
veins, hada number of stripes when a few days 
old. A figure of it is given, and it certainly has 
a very zebra-like appearance. At this point a 
less scientific investigator might have concluded 
that telegony was proved, and there was noth- 
ing further to be said. Not so Professor 
Ewart. He continued his researches, and in 
due time was able not only to show that such 
striping as that of Mulatto’s second foal was 
not uncommon in horses, but also to produce 
equally striped foals from mares which had 
never seen a zebra. 
In the course of the investigation, many facts 
of the greatest interest were ascertained. The 
hybrid between the Highland pony and Bur- 
chell’s zebra showed a striking likeness to the 
Somali zebra in the plan of its stripes. This is 
considered by Professor Ewart to indicate rever- 
sion, and in this connection excellent reasons 
are given for considering that the common 
ancestor of the various breeds of horses was 
striped, and that among zebras the Somali 
species is in many respects the most primitive. 
The whole question of reversion resulting 
from a cross is carefully discussed, and it is 
suggested when there is a sort of antagonism 
between the immediate parents or close ances- 
tors, the more or less remote ancestors might 
contribute more than their normal share to the 
new individual. That is to say, the two in- 
compatible parents annihilate one another, 
more or less, like the Kilkenny cats, and the 
ancestral traits, which otherwise would be 
crowded to the wall, come to the front. This 
sounds reasonable enough, but one may hazard 
a further suggestion that the two parents would 
contribute the same latent ancestral characters, 
but diverse modern ones, and so the characters of 
their common ancestor might be emphasized. 
Thus, let A be the characters of the common 
ancestor, and B and C the characters subse- 
quently acquired by the race represented by 
each parent. Then the union would be that of 
AB +- AC, which would give A the advantage, 
if for any reason B and C were less than or- 
dinarily powerful. Dr. Max Standfuss, in breed- 
ing hybrid moths (Hntomologist, 1900, p. 341), 
has found that the phylogenetically oldest 
