GENERAL INTRODUCTION. Ixxix 



meant to account for telegony by tlie saturation theory, 

 but evidently the saturation theory goes fui'ther than 

 telegony ; it seems to imply an actual change in the 

 organs and tissues of the dam, — she is said to be 

 " saturated with the sire's nature or blood ; " whereas, 

 according to Weismann, Romanes, and others, telegony, 

 if it occurs, only influences the germ-cells, which stand 

 in much the same relation to the parent that a cargo of 

 wheat does to the ship conveying it. Evidence of 

 saturation is looked for, not so much in a change in the 

 appearance of the female parent, though a change of 

 this kind is sometimes insisted on, as in the offspring. 

 They are said to become progressively more and more 

 like the sire, the second foal taking more after the sire 

 than the first, the third than the second, and so on. 

 Now, as it happens, a paper was read at the recent 

 Zoological Congress at Cambridge by Professor Hubrecht 

 of Utrecht, which seems to lend support to this theory 

 as well as to the telegony theory. The object of this 

 paper was to show that blood-corpuscles in some mammals 

 pass bodily from the foetus into the tissues of the dam. 

 It is not asserted that this happens in the mare ; on the 

 contrary, the inference is that in the horse, pig, and 

 certain other families this passage of the foetal blood- 

 corpuscles does not occur. But even if it be admitted 

 that the ''actual circulation" or blood of the unborn 

 foal is absorbed, it does not necessarily follow that the 

 nature of the dam is in any case gradually altered, 

 except in as far as the foetal corpuscles are the bearers 

 of the germs of disease. The saturation theory may 

 also be said to be supported by the recent investigations 

 of M. Charrin, who found that " diphtheritic toxins 

 injected into the embryos of a pregnant rabbit caused 

 the death of the mother on the fifth day ; " * and further, 

 that a rabbit could be rendered immune by injecting 

 protective toxins into the embryos. M. Charrin infers 

 from his experiments that the characteristics acquired by 

 the mother from one set of embryos could be handed on 

 * The Medical Press, October 5tli, 1898, p. 360. 



