1895.] The Symbiosis of Stock and Graft. 621 
produce any change either in color or form. In Strasburger’s 
experiment of grafting Datura on potato and getting atropin 
in the tubers, if the malformation of part of these tubers was 
due to the presence of atropin then it is a case of poisoning 
and not of a change in the specific nature of the stock due to 
the cion, as Strasburger also admits. From the observations 
of Lindemuth there can be no doubt that many of the reports 
of graft hybrids rest on errors. Master’s reported an exper- 
iment made by Maule of Bristol and exhibited a photograph 
showing Helianthus tuberosus grafted on H. annuus and the 
roots of the latter bearing tuberous growths. This experiment 
was repeated by M. Carriere, a very careful observer, and on 
the roots of his Helianthus annuus appeared two budless black 
swellings with a rifted surface, and in general resembling cer- 
tain dahlia tubers. In the vicinity of these were other forms 
which more nearly resembled the artichoke. This experiment 
should be repeated. Conclusion: Either there are no such 
things as graft hybrids or else they are limited to a small num- 
ber of plants. 
