MlSSlSSII'l'I E XI'l-:RlMICX'r STATION. 7 



■was dominant m nmsl df the external eliaracters • if tlic iTX'liriil, and a 

 study of internal struetun' shuwed a dinninanee i if this s] lecies there also. 



Groth (1911, liU'i), after an extended stud\- of the Inrni and struc- 

 ture of hylirids lietweiMi sexeral \-aneties of tinnatnes, eoneluded: 

 "Praeticalh- all the eharaeters studii'd tend tn exeeed tlie mean lietween 

 the \-alues of the ixirents, in the Fi nf the eniss, sri that the lea\'es of 

 the cross tend to In.' longer, narrower, and ])oss(.ss a ijreatcr number of 

 seginents than the mean between llu' \alues for the parents, or e\'en 

 than either of the jiarents themseh'es. In other words, the crosses 

 tend to be more \-i,i;-orons than the parents." Furtlier, he concludes; 

 "Reciprocal and diqilicate crosses usualh- aci'ce in the nilieritancc of 

 all characters studied; but the\- ma\- differ ,i;reatl_\'. E\-en plants 

 borne from the sceil uf one fnnt jiollinatcd b\- pollen from a .sinf^le 

 tdower may ditfer radically in characters of size, shape and numlier." 



Cannon (190!)), made a stud\- of the trichomcs of eleven different 

 species and hylirids of Ju,L;-lans, (Anot'i.jra, I\ipa\-er and Solanum 



Fig. 2. — Nicotiana sylvestris. 



