590 PROFRSSOR MARCUS HARTOG. 



I gave an account of the foregoing facts and theories at 

 the Dover Meeting of the British Association in 1900. The 

 greater part of this essay was typed and the Avhole of it 

 written out in notes during the autumn of that year. I had 

 kept it by me to form part of a wider discussion ; but I thinlc 

 that it comes fitly into print in company with the following 

 ]iappr on the phenomena of "fertilisation." 



B. — An Essay on Fertilisation. 



At the Southport Meeting of the British Association Pro- 

 fessor Hickson, President of Section T>, asked me at very 

 short notice to open a discussion on "Fertilisation" in the 

 section, to which I was about to contribute a note on the 

 " Significance of Progamic Fissions." The following pages 

 represent far more closely what I would have wished to say 

 than what I actually said. 



The word " fertilisation," like so many others in science, 

 has come down to us from the days of ignorance, undergoing 

 many changes of meaning, and acquiring new meanings by 

 accretion on its way. Undoubtedly it was originally used in 

 the sense in which we speak of a farmer fertilising his land — 

 it conveyed the idea that a female became fertile, or was 

 enabled to bear offspi-ing by a co-operative process on the 

 part of the male, and to this the name was applied. This 

 process is now distinguished, however, as " insemination " or 

 " fecundation ; " though in French the term " fecondation " 

 has acquired all the meanings of " fertilisation." When, 

 later on, the germ of the young animal was found always to 

 develop from the egg, the idea of the fertilising process was 

 transferred from the mother to the egg; and to-day we use it 

 to denote the process by which the egg, hitherto an inert 

 resting-cell, is induced to become active, and by divisions to 

 give rise to the young life of the germ. At first, we know, 

 this was nttributed to a mere emanation, the "aura 

 seminalis ; " but Spallanzani demonstrated 150 years ago that 



