EMBRYOLOGY 43 



species now become ill-suited to its habitat, or rather 

 with a better place opened to it in the economy of 

 Nature. It would not matter to the full-grown cat 

 whether in its young state it was more or less 

 eminently feline, so that it become so when full- 

 grown. No doubt most variation, (not depending 

 on habits of life of individual) depends on early 

 change l and we must suspect that at whatever time 

 of life the alteration of fetus is effected, it tends 

 to appear at same period. When we (see) a ten- 

 dency to particular disease in old age transmitted 

 by the male, we know some effect is produced 

 during conception, on the simple cell of ovule, 

 which will not produce its effect till half a century 

 afterwards and that effect is not visible 2 . So we 

 see in grey-hound, bull-dog, in race-horse and cart- 

 horse, which have been selected for their form in 

 full-life, there is much less (?) difference in the few 

 first days after birth 3 , than when full-grown : so in 

 cattle, we see it clearly in cases of cattle, which 

 differ obviously in shape and length of horns. If 

 man were during 10,000 years to be able to select, 

 far more diverse animals from horse or cow, I 

 should expect there would be far less differences in 

 the very young and foetal state : and this, I think, 

 throws light on above marvellous fact. In larvae, 

 which have long life selection, perhaps, does 

 much, in the pupa not so much 4 . There is no 



1 See the discussion to this effect in the Origin, Ed. i. pp. 443-4, vi. p. 

 610. The author there makes the distinction between a cause affecting the 

 germ-cell and the reaction occurring at a late period of life. 



2 Possibly the sentence was meant to end " is not visible till then." 



3 See Origin, Ed. i. pp. 444-5, vi. p. 611. The query appended to much 

 less is justified, since measurement was necessary to prove that the grey- 

 hound and bulldog puppies had not neai'ly acquired " their full amount of 

 proportional difference." 



4 (The following discussion, from the back of the page, is in large measure 

 the same as the text.) I think light can be thrown on these facts. From the 

 following peculiarities being hereditary, [we know that some change in the 

 germinal vesicle is effected, which will only betray itself years after] diseases 

 man, goitre, gout, baldness, fatness, size, [longevity (illegible) time of 



