398 BOTANICAL GAZETTE ' [juxe 



Inoculations from Dracaena and Coffea to the apple were entirely 

 successful; those from watermelon and bean to the apple were failures. 

 Inoculations from Asclepias to the apple caused infection, but the 

 resulting diseased area looked different from the true bitter rot; no 

 pustules were formed. Inoculations from orange to the apple were 

 successful, but the spot formed was very different from that formed 

 by the bitter rot fungus- The pustules were steel gray, hairy, and 

 raised from the surface {jig. g), and seemed to be identical with the 

 pustules formed by the guava anthracnose on apple, as described by 

 Sheldon (37). 



While these inoculation experiments are not yet so complete as 

 they should be, they show that we have a number of forms that will 

 grow on different hosts. Whether these different forms occur normally 

 on the different hosts is another qnestion. It is certain also that 

 there are some forms which cannot be transferred to some of the 

 other plants that are normally infected with anthracnose; for 

 example, the bean anthracnose on apple. 



ADAPIATION 



After one has studied many of these forms for some time and ob- 

 served the slight difference between them, and after he has watched 



sure 



arise. It is difficult after such a study as the above, w'here variations 

 take place in a few months, to beheve in the fixity of species. Among 

 higher plants some forms are constantly changing, and breeders 

 can now build up a new variety in a few years. If such things are 

 possible in a few generations with higher plants, how much mere so 

 must it be with the lower forms, that pass through a generation in a 

 week and may have many generations in a season. These lower 

 forms are excellent organisms with which to study variation, and 

 considerable work of this kind has been done with the bacterial and 

 yeast organisms. Haxsen (28) in working with yeasts was able to 



them 



where'spore formation was impossible; the varieties became fixed and 

 would not again under any conditions produce spores. He ha 

 been able to build up fixed varieties differing from the parent 

 in shape of ceUs and power of fermentation. 



form 



