HEREDITARY INFLUENCE. 715 
in the water than in the soda water, more in the soda water 
than in the ginger beer. 
According to Rush (quoted by Lucas), the Danes, inter- 
marrying with women of the East, always produce children 
resembling the European type ; but the converse does not 
hold good when Danish women intermarry with the men of 
the East. Klaproth observes the same in the mingling of 
the Caucasian and Mongolian races. Girou, after five-and 
twenty years 5 experience in the breeding of sheep, found this 
“potency” destroy his calculations. He fancied that, by 
means of his Roussillon sheep and the Merino rams, he 
could sooner arrive at the fineness of wool which distinguishes 
the Merino, than if he coupled the Aveyron sheep with the 
Merino rams ; but he found that the Roussillon type resisted 
the Merino so energetically that, after a quarter of a century 
of successive crossings, it still reappeared, whereas the 
Aveyron sheep had long ceased to be distinguishable from 
the Merinos. The same potency of particular species is 
noticeable in plants. Koelreuter is quoted by Burdach as 
having fecundated the Nicotiana paniculata with the pollen of 
N, rustica ; and the hybrids thus produced were fecundated 
with the pollen of N. paniculata , but the plants resembled the 
N. rustica . On reversing this experiment, he still found the 
female N. rustica to have the preponderance ; so that, cross 
the species how he would, the N, rustica showed most 
potency. 
But although we thus see that race has a marked pre- 
ponderance, we must also remember that it is subject to the 
individual variations of vigour, health, age, &c. Girou sums 
up his observations with this general remark : the offspring 
of an old male and a young female resembles the father less 
than the mother in proportion as the mother is more vigor- 
ous and the father more decrepit ; the reverse is true of the 
offspring of an old female and a young male. In fact, if we 
consider that the offspring reproduces the organization of 
its parents, and, consequently, the organization of that parti- 
cular period , we see at once that age, health, and general 
potency of organization, must be taken into the account of 
complicating causes. This also will help to explain — but 
not wholly explain — the great differences observable in the 
same family : differences of sex, of strength, and appearance. 
At present, however, science can only take note of it as a 
“perturbing influence. 5 ’ 
Our survey of this great subject, brief though it has been, 
has enabled us to note four general facts, which sum up the 
