VENATION AND SENESCENCE OF POLYEMBRYONIC CITRUS PLANTS 325 
show any differences in size and vigor? If there is a difference, to what is it 
due? 
» Webber (1900) found that, when Citrus aurantiiim was crossed with 
C. trifoliata, among polyembryonic seedhngs one plant would usually show 
intermediate characters common to both parents. This seems to leave no 
doubt but that such a plant had its origin from the fertilized egg. This 
hybrid, furthermore, was usually larger than the other plants according to 
Webber, who attributes the difference in vigor to the beneficial results of 
crossing. This is explicable on the ground that when hybridization is 
effected between parents of distinctive characters, new combinations of 
characters often result which are more favorably adapted to the environ- 
■J 
Fig. 5. Photograph showing 4 pairs of polyembryonic seedlings of C. grandis. Nos. 
I and 2 show polyembryonic plants of unequal size. The relative size of attendant coty- 
ledons in no. 2 are easily seen. The size of cotyledons is evidently correlated with the 
size of the plants. No. 4. Polyembryonic plants of equal size and vigor (one-year-old 
seedlings). No. 5. Polyembryonic plants of equal size. They are three years old and 
chlorotic. 
ment than are those of either parent. This greater vigor has often been 
mistaken for an indication of rejuvenescence. 
Among all the seedlings of Citrus grandis grown in the greenhouse, 
there were no true hybrids, as far as the writer observed. Yet in many 
