io8 PROBLEMS OF GENETICS 



by the results of this series of experiments in stating that the 

 "Bild," as he terms it, or composition of the male and female 

 sides of these two species, biennis and muricata, are distinct. 

 On the evidence before us it is not, however, possible to form a 

 perfectly clear idea of each, and until details are published, a 

 reader without personal knowledge of the material cannot do 

 more than follow the general course of the argument. For fuller 

 comprehension a proper analysis of the characters with a clear 

 statement of how they are distributed among the several types 

 and crosses is absolutely necessary. According to de Vries the 

 female of biennis possesses a group of characters which he defines 

 as "conica" in allusion to the shape of the flower-buds. Besides 

 the conical buds, this group of features includes imperfect 

 development of wood, rendering the plant very liable to attacks 

 of Botrytis, and comparatively narrow leaves. 



The female of muricata carries a group of features which he 

 calls "frigida" and, though this is not quite explicitly stated in a 

 definition of that type, it is to be inferred 6 that its characteristics 

 are regarded as greater height, strong development of wood with 

 comparative resistance to Botrytis, and broad leaves. 



The characters borne by the male parts of the two species 

 are in general those by which they are outwardly distinguished. 

 For example, the leaves of Oe. biennis are comparatively broad 

 and are bright green, while those of muricata are much narrower 

 and of a glaucous green, and I understand that de Vries regards 

 these properties as contributed by the male side in each case and 

 to be carried by the male cells of each species. The suggestion 

 as regards biennis and muricata comes near the conception often 

 expressed by naturalists in former times (e. g., Linnaeus) and 

 not rarely entertained by breeders at the present day, that the 

 internal structure is contributed by the mother and the external 

 by the father. 



On the other hand, the offspring of each species when used 

 as mother is regarded as possessing in the main the features of 

 the maternal "Bild," but the matter is naturally complicated 

 by the introduction of features from the father's side, and it is 



6 From the description of the offspring of muricata used as mother. 



