I06 AMPHIMIXIS OR ESSENTIAL MEANING OF [XII. 



the field. Such a view must inevitably have been brought 

 forward, if we were ever to arrive at a solution of the phenomena. 

 I should certainly be the last to reproach the three savants 

 who developed this hypothesis, although I have perhaps 

 contributed something towards the proof of its unsoundness. 

 The path to truth often lies through inevitable error. 



I was, from the first, predisposed against the view of Minot, 

 Balfour, and Edouard van Beneden, being influenced not only 

 by certain isolated phenomena of inheritance, phenomena which 

 were at a later time and with perfect justice, urged against it, 

 but by the facts of inheritance taken as a w^hole, and by that 

 conception as to the nature of fertilization to which I had even 

 then been driven by these very facts, although unable to prove 

 to myself, or to others, the soundness of my views. 



We recognize tw^o phenomena in amphigonic reproduction : — 

 first, fertilization in its strictest sense, i. e. the fact that the ovum 

 can only develope into a new being when it has united with the 

 spermatozoon, after which union a ' vitalization of the egg' 

 takes place (Hensen) ; secondly, the mingling of two hereditary 

 tendencies. From the very oldest times it must have been 

 observed that the peculiarities of the father as well as of the 

 mother, may appear, and to an equal extent, in the children. 

 Such transmission was conceived by some writers in a material 

 sense ; for they imagined a part of the substance of the mother 

 or of the father as the basis of the body of the offspring ; but it 

 was also looked upon by others as simply the transmission of an 

 impulse. Thus according to Aristotle the father confers the im- 

 pulse to movement, while the mother contributes the material. 

 Lowenhoek and the other ' spermatists ' held that the semen 

 alone forms the substance of the embryo, while his opponents, 

 Swammerdam and Malpighi, the so-called 'ovists,' returned 

 to Aristotle's view in so far that they believed that the mother 

 gives rise to the substance, that is the ovum, while the male 

 influence is limited to an 'aura seminalis,' which at the same 

 time acts as the transmitter of movement. 



Some writers regard inheritance by means of fertilization 

 as a purely immaterial occurrence : thus Harvey, in his 

 remarkable and minutely thought-out theory of heredity, 

 imagined conception as a mental process, the folds of the 

 mucous membrane lining the uterus corresponding to the 



