BIOCHEMICAL STUDIES OF HYBRIDS 



311 



Morphological differences and oil-character differences of a 

 rather clear-cut nature exist among the two species (see chart below). 



Not much specific data on the morphological character of the 

 hybrids was available, since most tables and figures which were in- 

 cluded related to oil characters. However, the data presented show 

 that leaf shape among hybrids varied from one parental type to the 

 other with most individuals falling in between. According to the 

 authors, morphological characters show marked segregation and re- 

 combination, and hybrid individuals appeared which resembled either 

 parent together with a series of intermediates between them. 



Inheritance of oil characters 



IN HYBRIDS OF Eucalyptus macarthuri X £• cinerea: 



Oil yield, as already observed, is high in E. cinerea and low 

 in E. macarthuri. In the hybrids, oil yield was in every case low, en- 

 tirely within the range of E. macarthuri. 



Qualitatively, the oils in the two species differ as follows (only 

 the prominent differences are included). E. macarthuri produces large 

 amounts of geranyl acetate but no cineole while E. cinerea produces 

 large amounts of cineole and no geranyl acetate. Both species produce 

 some eudesmene and sesquiterpene, and E. macarthuri produces signif- 

 icantly more eudesmol than does E. cinerea. Since cineole and geranyl 

 acetate involve strict reciprocal presence-absence, these substances 

 are studied most profitably in the hybrids. 



The hybrids showed, unequivocally, recombination of the oil 

 characters of the parents by virtue of the presence of geranyl acetate 

 and cineole together in six cases. From Table 15-1, it appears as though, 



