260 WALTON. 



the offspring of normal unions have qualities of both parents. If, how- 

 ever, the female plastochondria do not carry such determinants, as 

 Boveri's work shows, then we are not justified in supposing that the 

 male plastochondria do. 



From this evidence it seems clear that the plastochondria, or the 

 so-called 'mitochondria,' can not be true 'plasma bearers of heredity,' 

 at least in the nematodes Ascaris canis and Ascaris megalocephala, as 

 well as in the cases studied bv Lillie and bv Boveri. 



Summary. 



(1) The 'refractive body' is formed by the fusion of the 'refringent 

 vesicles.' 



(2) The 'refringent vesicles' are formed from the cytoplasm of the 

 spermatocytes through the action of small extruded granules of karj'o- 

 chromatin, the ' karyochondria ' of ^Yildman. 



(3) The 'refractive body' in Ascaris canis Werner takes no part 

 in the fertilization of the egg other than as a source of food supply to 

 the spermatozoon between the time of copulation and the time of 

 insemination. 



(4) The 'plastochondria' are partly of plastosomal and partly of 

 karyochondrial origin through their formation in the 'refringent 

 granules.' 



(5) The ' plastochondria ' (mitochondria) are not ' plasma bearers of 

 heredity ' in Ascaris canis Werner. 



I 



