S*CT. XXXIX. 4. GENERATION. 563 



times exifts, is evinced by the double yolks in fome 

 eggs, which I fuppofe were thus formed previous to 

 their impregnation by the exuberant nutriment of 

 the hen. 



This idea is confirmed by the analogy of the mon- 

 flers in the vegetable world alfo ; in which a dupli- 

 cate or triplicate production of various parts of the 

 flower is obfervable, as a triple pedtary in fome co- 

 lumbines, and a triple petal in fome primrofes ; and 

 which are fuppofed to be produced by abundant nou- 

 rimment. 



5. If the embryon be received into a fluid, whofc 

 ftimulus is different in fome degree from the natu- 

 ral, as in the production of mule-animals, the new 

 irritabilities or fenfibilities acquired by the increaf- 

 ing r growing organized parts may differ, and 

 thence produce parts not fimilar to the father, but 

 of a kind belonging in part tp .the mother ; and thus, 

 though the original ilamen or living ens was de- 

 rived totally from the father, yet new irritabilities or 

 fenfibilities being excited, a change of form corref- 

 ponding with them ^will be produced. Nor could 

 the production of mules exift, if the flamen or 

 miniature of all the parts of the embryon is previ- 

 ouily formed in the male femen, and is only dif- 

 tended by nou rimment in the female uterus. Where- 

 as this difficulty ceafes, if the embryon be fuppofed 

 to confift of a living filament, which acquires or 

 makes new parts with new irritabilities, as it ad- 

 vances in its growth. 



The form, folidity, and colour, of the particles 

 of nutriment laid up for the reception of the firft 

 living filament, as well as their peculiar kind of 

 ftimulus, may contribute to produce a difference in 

 the form, folidity, and colour of the fetus, fo as 

 to referable the mother, as it advances in life. This 

 alfo may efpecially happen during the firft ftate of 

 the exiftence of the embryon, before it has ac- 

 quired 



