362 



GENERAL BIOLOGY 



were being destroyed by the imported American grape 

 phylloxera (a root infesting aphid, Phylloxera vastatrix), 

 the situation was saved largely by grafting wine grape 

 cions on stocks of the hardier and immune American 

 grapes. 



2. To perpetuate in the fruiting part of the combination 

 a valuable variety; one that does not breed at all, (as for 

 example, a seedless grape or orange) or one that does not 

 breed true. In such case the kind of stock used is of little 

 consequence, except as it is a good feeder for the cion. 



Grafting in animals. — Such combinations of parts are not 

 so readily made in animals. The specialized contractility 

 of the animal body is against it. It is harder to keep the 

 growing parts in close apposition, while being knit together. 

 Advantage may be taken of quiescent periods in the life of 

 the individual when stored food is available for growth, such 

 as the early embryonic stages of frogs (fig. 212) and the pupal 



stages of insects, etc. Thus 

 moth pupae of the right age 

 carefully cut in two across 

 the base of the abdomen, and 

 carefully handled to prevent 

 loss of blood have been united 

 successfully in cross-combi- 

 nations, the parts being 

 sealed with paraffine while 

 being knit together. An- 

 tennae, and wings have been 

 cross-grafted in similar man- 

 ner. By uniting male bodies 

 with female abdomens, fe- 

 males having the appearance of males have been produced. 

 Similarly, male and female wings and antennae have 

 been combined upon the two sides of one individual. 



Fig. 212. Diagram of grafting 

 operation on frog larvae (after 

 Harrison), a, the larva at suit- 

 able age for grafting; b, the 

 same larva, older, to which has 

 grafted the tail of a larva of 

 another species. 



