2oii PH1L.OSOPH1CAL NOTES ON 



twenty years ago, were the more lirinly impressed in the minds oi 

 biologists by the recently-acquired knowledge of fertilization or 

 impregnation. Then comes the demonstration, by Siebold, of the 

 capacity for development of true eggs, even when not impregnated. 

 The sharpness of the limit between buds and eggs was by this 

 at once destroyed ; and the closely -following researches of Leydig 

 (antecedent to Siebold's work in some cases), Huxley, Lubbock, 

 and Leuckart, on the structure of the supposed buds of aphis and 

 allied insects, and of lower crustaceans, proved that these bodies 

 were morphologically ova, originating in ovaries, and having the 

 essential structure of fertilizable ova." 



Prof. Huxley introduced the name of pseudova for these egg- 

 like buds. But, in a note, Prof. Ray Lankester says : — " The 

 falsity implied in the prefix seems to make a rather stronger 

 distinction than is desirable between any of these bodies, for they 

 are all truly ova, though ova of various special properties." 



Prof. Lankester then goes on to say : — " Whilst, then, up to 

 this period such a thing as parthenogenesis appeared to be a 

 strange exception, the question has now shifted, and since the 

 essential identity in reproductive power of cuttings, buds, pseudova, 

 and eggs is proved, the problem before naturalists is rather ' Why 

 are eggs ever fertilized ? ' in short, ' What is the use of the male 

 sex at all ? ' We have animals and plants multiplying by fission, 

 breaking up into two or more parts, each of which l^ecomes a new 

 individual ; w^e have them giving rise by growth to masses of cells, 

 which become detached, or remain attached, and develoj)ing each 

 into a new individual ; and, finally, we have them elaborating 

 single large cells, which become detiiched and develop each into a 

 new individual. Why should it be that, in certain cases, these 

 last require fusion before they develop ? . . . . Mr. Darwin has 

 suggested the most satisfactory theoi-y of fertilization in assigning 

 to it the object of fusing two life-experiences in the progeny, 

 which thus gains tendencies and acquires impulses from a wider 

 area than does an unfertilized ovum, and is in so far strengthened." 



Prof. Weismann has endorsed Darwin's supposition. He con- 

 siders that the object of fertilization is the creation of variation, 

 through the " fusion of two different life-experiences." Thus, 

 through each cross, fertilization -germs are collected in one cell from 

 wider and wider areas, so that we get inheritances not only of 



