1900-1.] Mr F. H. A. Marshall on Hair in the Equidoe. 387 
Sections through the hairs of the hybrid offspring “Sir John,” on 
the other hand, are in no way suggestive of those from the dam, 
but closely resemble those of the hybrids “Black Agnes” and 
“ Brenda,” one of which is figured (fig. 10). Professor Ewart has 
given reasons for the conclusion that of the existing species of 
zebras the Somali zebra approaches nearest to the ancestral type. 
He has also shown that the markings of the hybrids resemble the 
markings of the Somali zebra much more closely than those of the 
BurcheLTs zebra, and this resemblance he has ascribed to reversion. 
Now it cannot be said that the shoulder hairs of the hybrids, either 
in their shape, length, which is rather variable, or in the arrange- 
ment of the pigment, are at all suggestive of the same hairs in the 
Somali zebra. When, however, we compare the hairs of the mane 
the case is quite different. A section through a hair of the mane 
of a hybrid, such as the one figured, which is through such a hair 
in “ Brenda,” which in the mane hair characters is quite typical of 
the hybrids, shows a fairly even distribution of pigment and a 
circular line of demarcation between cortex and medulla, which are 
also what we find in a mane hair section from the Somali zebra. 
There is very little of that tendency of the pigment to become 
more thickly distributed towards the interior of the cortex, such as 
I have found in all sections through mane hairs of the Burchell’s 
zebra. This is a curious result, and may, perhaps, like the 
peculiarities of the striping, be ascribed to reversion to the more 
ancestral type. 
The Telegony Hypothesis. 
Nathusius suggested that if the telegony hypothesis, or the 
hypothesis that subsequent offspring are infected by a previous sire 
be correct, we might expect to find evidence of it in the character 
of the hairs of the subsequent offspring. We have such a subsequent 
offspring in Professor Ewart’s “Circus Girl.” In 1897 the dam 
“ Tundra ” gave birth to a hybrid, “ Hecla.” In 1898 the subse- 
quent foal “ Circus Girl ” was bom, the sire being a bay Shetland 
pony. Just as “Circus Girl,” both in make and colour, closely 
resembles her mother, so the hairs of the two animals are almost 
identical in character, and sections through the hairs of the manes 
are quite indistinguishable. There is nothing whatever suggestive 
