Experiments in Grafting 301 



Crampton has studied the effects of uniting parts of different 

 species of moths. The pupae of the species to be united were cut 

 across, and the exposed surfaces brought into contact and held 

 in place by a coating of paraffin. In successful cases the parts 

 united, at least so far as the integumentary organs are concerned, 

 and the moths that subsequently emerged were made up of parts 

 of two species. As a rule, each part developed its own specific 

 coloring, showing no mutual influence of the parts on each other. 

 In two cases, however, evidence of some influence was found. 

 The posterior part of the abdomen of a female pupa of Callosa- 

 mia promethea was united to the rest of the body of Samia 

 cecropia. In the moth the promethea part assumed the color 

 of the cecropia. In another union between Telea polyphemus 

 and Samia cecropia the small piece of the latter assumed the 

 color of the former. According to Mayer, the color in these 

 moths is largely due to the drying of the haemalymph. The 

 explanation of the two cases just given may be that some 

 of the haemalymph of the larger component got into the smaller 

 part. If the result is due to this, the outcome is only remotely 

 connected with the "influence" of one part on another. 



In conclusion, it is apparent that grafted pieces of different 

 species have no mutual influence on each other of the kind that 

 characterizes species. In this respect the results are quite differ- 

 ent from the effects of cross-fertilization ; the difference is prob- 

 ably due to the actual union within the same cell of the characters 

 of the two parents in cross-fertilization, and to the absence of 

 any such intimate fusion in the case of grafting. In other words 

 the cells retain their specific characters in the unions by graft- 

 ing, and although cells of different species may live side by 

 side and form a part of a new individual, they have no influ- 

 ence of a specific nature on each other. 



Special Problems of Development 



It has been pointed out that by means of grafting it has been 

 found possible to study the question of self-development versus 

 correlated development of parts of the embryo. In most cases 



