CRITICISM OF OWEN'S THEORY. 305 



not cells at all. Ou this latter point it may be observed 

 that embryologists are still divided,* the dispute turning on 

 the correct definition of a cell — much as if men disputed 

 whether a book " in sheets " ought properly to be called a 

 " book." As regards Owen's theory, a slight modification in 

 its terms would meet the objection. 



Not so the objection which must, I think, be raised against 

 the vital point in the theory — the assumption of a definite 

 prolific force contained in the primary germ-cell, a force 

 which becomes diluted by subdivision of the cell, and can be 

 renewed only through another act of fertilisation. This is 

 the heel of Achilles ; if vulnerable here, our great anatomist 

 may be pricked by any vulgar javelin. Let us try. "The 

 physiologist," says Owen, " congratulates himself with jus- 

 tice when he has been able to pass from cause to cause, 

 until he arrives at the union of the spermatozoon with 

 the germinal vesicle as the essential condition of develop- 

 ment — a cause ready to operate when favourable circum- 

 stances concur, and without which cause those circumstances 

 would have no effect. What I have endeavoured to do has 

 been, to point out the conditions which bring about the 

 presence of the same essential cause in the cases of the 

 development of an embryo from a parent that has not itself 

 been impregnated. The cause is the same in kind, though not 

 in degree ; and every successive generation, or series of spon- 

 taneous fissions of the primary impregnated germ-cell, must 



* See the latest work on the subject : Fcnke's Lchrhuch der Phjsiologie, 

 p. 136G, el seq. 



2 C 



