HEREDITARY TRANSMISSION AND VARIATION. 85 



the body and the tail ; and if you cut off the tail, you 

 will find that that will reproduce the body and all the 

 rest of the members, without in any way deviating 

 from the plan of the organism from which these por- 

 tions have been detached. And so far does this 

 that some experimentalists have carefully examined 

 the lower orders of animals, — among them the Abbe 

 Spallanzani, who made a number of experiments upon 

 snails and salamanders, — and have found that they 

 might mutilate them to an incredible extent ; that you 

 might cut off the jaw or the greater part of the head, 

 or the leg or the tail, and repeat the experiment sev- 

 eral times, perhaps, cutting off the same member again 

 and again ; and yet each of those types would be 

 reproduced according to the primitive type : nature 

 making no mistake, never putting on a fresh kind of 

 leg, or head, or tail, but always tending to repeat and 

 to return to the primitive type. 



It is the same in sexual reproduction : it is a mat- 

 ter of perfectly common experience, that the tendency 

 on the part of the offspring always is, speaking broadly, 

 to reproduce the form of the parents. The proverb 

 has it that the thistle does not bring forth grapes ; so, 

 among ourselves, there is always a likeness, more or 

 less marked and distinct, between children and their 

 parents. That is a matter of familiar and ordinary ob- 

 servation. We notiee the same thing occurring in the 

 cases of the domestic animals — dogs, for instance, and 

 their offspring. In all these cases of propagation and 

 perpetuation, there seems to be a tendency in the off- 

 spring to take the characters of the parental organisms. 

 To that tendency a special name is given — and as I 

 may very often use it, I will write it up here on this 



