Evidence from Somatic His to gene sis 35 



drial theory of heredity. The meager observational support 

 for the hypothesis that these particular cell members are 

 generally bearers of heredity relieves us from the necessity 

 of examining it in any such detail as we examined the chro- 

 mosome theory. But there are several things about it of 

 so much importance that we must look into it somewhat. 

 The name mitochondria was first used by Benda for a "new 

 cell organ, perhaps serving a specific function." Benda's 

 original view was that the function served is that of the 

 motility of the cell. But in a later publication he presented 

 observations which seemed to him conclusive proof that the 

 mitochondria of the sperm are situated in parts of it which 

 enter the egg at fertilization. This last suggestion gave 

 an added impulse to the study of the bodies occurring in the 

 cytoplasm and soon many new names were applied to them, 

 for they were soon found to present differences in size, 

 shape, and reaction to chemicals. It seems, however, that 

 the present state of knowledge justifies us in applying to 

 them all the one term, mitochondria, though without imply- 

 ing that they are all exactly alike. They may be held to 

 be generically alike but specifically different. 



The first investigator to set up definitely the hypothesis 

 that cytoplasmic elements of this class are bearers of hered- 

 itary qualities seems to have been Meves. 



Only a few of the very many investigations since devoted 

 to the subject can be noticed, these being selected for their 

 bearing on particular aspects of the problem. In the first 

 place, the position of Meves himself is important. Accept- 

 ing the assumptions formulated by O. Hertwig in 1875 of a 

 "substance which carries over the beginnings (Anlagen) of 

 the parents to the child," and that "this substance exists 

 (in the germ-cells) in an original, histologically undifferen- 

 tiated condition" ; 3 and adding his own reflection that not 

 all the cytoplasmic parts of the spermatozoon (for example, 

 the axial fiber of the tail) possess inheritance potencies, he 



