HEREDITARY TRANSMISSION AND VARIATION. 91 



been very carefully studied. Now, the curious thing is 

 this, that although you have the same elements in 

 the experiment in each case, the offspring is entirely 

 different in character, according as the male influence 

 comes from the Ass or the Horse. Where the Ass is 

 the male, as in the case of the Mule, you find that the 

 head is like that of the Ass, that the ears are long, the 

 tail is tufted at the end, the feet are small, and the 

 voice is an unmistakable bray ; these are all points 

 of similarity to the Ass ; but, on the other hand, the 

 barrel of the body and the cut of the neck are much 

 more like those of the Mare. Then, if you look at the 

 Hinny, — the result of the union of the Stallion and 

 the she-Ass, then you find it is the Horse that has the 

 predominance ; that the head is more like that of the 

 Horse, the ears are shorter, the legs coarser, and the 

 type is altogether altered ; while the voice, instead of 

 being a bray, is the ordinary neigh of the Horse. 

 Here, you see, is a most curious thing : you take 

 exactly the same elements, Ass and Horse, but you 

 combine the sexes in a different manner, and the result 

 is modified accordingly. You have in this case, how- 

 ever, a result which is not general and universal — there 

 is usually an important preponderance, but not always 

 on the same side. 



Here, then, is one intelligible, and, perhaps, neces- 

 sary cause of variation : the fact, that there are two 

 sexes sharing in the production of the offspring, and 

 that the share taken by each is different and variable^ 

 not only for each combination, but also for different 

 members of the same family. 



