14 
Hybridization of Vitis Rotundifolia 
are here several interdependent characters. Changes affecting one of 
them therefore will to some extent influence the others. Where the 
degree of inheritance of the intermediate condition is uniform for 
each character of the individual, there is a stem that is fairly uniform 
in its composition. On the other hand, where the degree of inheritance 
of the different characters varies for the individual, the influence of 
the related characters results in a complex condition. It is necessary 
to consider this on the basis of the generative tissue of the cambium. 
It would appear that the cambium varies in its hereditary composition, 
a difficult thing to explain or believe. 
It would probably be advisable if possible to determine the immedi¬ 
ate causes influencing the formation of hard bast in the phloem, and 
the formation of phellogen. Knowing these influences, it might be 
possible to find a hereditary factor or factors which would control these 
characters. 
In regard to the formation of phellogen, Douliot (5) finds that the 
cork in the stem may be superficial, pericylic or intermediate in origin. 
In the parents of the crosses described here, the Euvitis species have 
the cork cambium pericylic, and the Muscadinia species superficial. 
However, the lack of an intermediate condition for this character in 
the hybrids of the Ei generation but rather a proliferation of suber- 
ized tissue would indicate the inheritance of a tendency to form cork 
cambium in both locations. 
Priestley (6) has studied the formation of phellogen from the casual 
standpoint, finding that it is related to “1, the blocking of a parenchy¬ 
matous surface usually by a deposit of suberin or cutin formed in the 
presence of air; 2, the accumulation of sap at the parenchymatous 
surface thus blocked; 3, the consequent development and activity of a 
phellogen amidst this parenchyma.” This would hold true in the case 
of the parents of these hybrids. In Muscadinia species the sap can 
move outward in the stem to the epidermis where it is blocked and phel¬ 
logen subsequently formed. In the Euvitis stem the cortical cells are 
destroyed during the expansion of the stem and air enters as deep as 
the endodermis and the cork cambium is formed here. In the livbrids 
«/ 
where a combination of these conditions exist, it is difficult to explain 
phellogen formation as due to these causes, especially in those cases 
where there is a layer of isolated phellogen around a bundle of scleren- 
chyma fibers, or where there are two layers of phellogen. In other 
cases it would appear that the location of the cork cambium depended 
on the ability of the cortical cells to multiply and thus present a layer 
of parenchymous cells impervious to the air. Such an explanation 
practically removes the phellogen from direct inheritance by hereditary 
factors, the hereditary factors controlling only the cambium and the 
tissues formed by it, and the phellogen formation being controlled by 
air and moisture. 
The significance of the different degree of intermediate inheritance 
