SO.MK KESl'LTS OF OSTRICH INVESTIGATIONS. 



V7 



blage the chances of a clawed bird mating with another clawed 

 one are very remote. 



The experiments therefore prove that the absence of the 

 claw represents the loss of one or more genetic factors from the 

 germ plasm, but the various stages show that the claw factor 

 undergoes a gradual loss in potency. There is every reason to 

 expect that in time the claw on the fourth toe will disappear from 

 the entire ostrich race, as is seen to be the case with the claw 

 of the third finger. 



The large scales on the ujjper surface of the toe form a 

 continuous series, usually eight to ten in number. (Fig. 3.) 

 They cover only a small part of the toe, while comparison with 

 other birds would lead us to expect they would extend the whole 



1- ig. 



length, and be in continuity with the large scales along the tarsus. 

 It may be presumed that the factors for the missing scales have 

 wholly disappeared from the germ plasm, for no evidence of 

 them is ever forthcoming, not even in the embryo. Along with 

 the claw, they may be deemed to afford so nuich evidence in 

 support of the degeneration of the fourth toe. 



Ihivd Middle Toe. 



The large toe of the ostrich is the third or middle of the 

 ]>entadactyle foot, and, as the only other toe remaining is shown 

 to be well on the way towards disappearance, it is highly 

 l)robabl€ that in time tlie l)ird will be dependent upon this toe 

 .- lone. Certain strrctural facts ])resented by it, however, give 



