246 POPULAR SCIENCE MONTHLY. 



not quite abreast of the anatomical knowledge of his time, since, correct 

 as Harvey's main conclusions were, the observations upon which he 

 based them had already been superseded. Chiefly, however, Maupertuis 

 rests his case upon the facts of double heredity and hybridism. If the 

 embryo be truly ' predelineated ' in the ovum or in the 'zoosperm,' how, 

 he asks, can it come about that it inherits the specific or individual 

 characters of now one and now the other parent, and often of both? 

 The preformationists had, of course, their devices for explaining away 

 this pretty obvious difficulty; but Maupertuis finds it easy to show that 

 the explanations are altogether inadequate when they are compared with 

 even the common and easily observable facts of heredity. His reasoning 

 is especially effective when he cites his own investigation of the trans- 

 mission of hexadactylism (sexdigitisme) through several generations 

 of a certain German family whose records he had examined, and points 

 out how little the preformation hypothesis could account for the trans- 

 mission of such a peculiarity through male and female parents alike, 

 its progressive disappearance as succeeding generations more and more 

 intermarried with persons having the normal number of digits, and its 

 occasional atavistic reappearance in remote descendants. In view of 

 these classes of facts, he declares, the encasement theory must be 

 abandoned, and the conclusion must be accepted that the embryo is 

 no ready-made article, preexistent from the creation of the world, but 

 a new birth, the product of a true genesis; — not, indeed, a genesis of 

 life itself, but of a new and unique combination and intermingling of 

 already-living elements contributed by both parents alike. These argu- 

 ments and this conclusion, it should be remembered, were advanced 

 by Maupertuis more than a decade before the publication of the great 

 work of Kaspar Friedrich Wolff,* from which the modern revival of 

 the doctrine of epigenesis is usually dated. The conception of epi- 

 genesis held by Maupertuis, was, moreover, far more complete and 

 accurate than that which Harvey had put forward a century earlier. 

 For although Harvey had asserted marem et foeminam pariter effi- 

 cient es causas esse generationis, he had denied that there can be any 

 physical interpenetration of ovum and spermatozoon, and had declared 

 that fecundation consists in the communication of a purely immaterial 

 force. It was in order to make this a little more intelligible that 

 Harvey had worked out his famous analogy between the conception of 

 the embryo in the uterus, and the conception of an idea in the brain. f 

 All this, Maupertuis remarks, is an idee etrange; where we have double 



* ' Theoria Generationis,' 1759. 



t Harvey's reason for this opinion lay in his failure to discover any traces 

 of the spermatozoon in the uterus. His own words are ' Quoniam nihil sen- 

 sibile in utero post coitum reperitur; et tamen necesse est ut aliquid adsit, 

 quod foeminam foecundam reddat; atque illud, ut probabile est, corporeum esse 

 nequeat: superest ut ad mcrum conceptum, specierumque sine materia recep- 

 tionem, confugiamus,' i. c, the ovum is fertilized by being impregnated with a 

 general concept! ('De generatione animalium,' 33). 



