WHAT WE MIGHT EXPECT. 175 



I submit that what I have written above supplies a 

 very fair primd facie explanation. 



Mr. Darwin continues : 



" Lastly, an embryo may be developed, and then perish 

 at an early period. This latter alternative has not been 

 sufficiently attended to ; but I believe, from observa- 

 tions communicated to me by Mr. Hewitt, who has had 

 great experience in hybridising pheasants and fowls, 

 that the early death of the embryo is a very frequent 

 cause of sterility in first crosses. Mr. Salter has 

 recently given the results of an examination of about 

 five hundred eggs produced from various crosses be- 

 tween three species of Gallus and their hybrids ; the 

 majority of these eggs had been fertilised ; and in the 

 majority of the fertilised eggs, the embryos had either 

 been partially developed, and had then perished, or 

 had become nearly mature, but the young chickens 

 had been unable to break through the shell. Of the 

 chickens which were born more than four-fifths died 

 within the first few days, or at latest weeks, ' without 

 any obvious cause, apparently from mere inability to 

 live,' so that from the five hundred eggs only twelve 

 chickens were reared " (" Origin of Species," 249, ed. 

 1876). 



No wonder the poor creatures died, distracted as they 

 were by the internal tumult of conflicting memories. 

 But they must have suffered greatly ; and the Society 

 for the Prevention of Cruelty to Animals may perhaps 

 think it worth while to keep an eye even on the em- 

 bryos of hybrids and first crosses. Five hundred crea- 

 tures puzzled to death is not a pleasant subject for 



