476 BOTANICAL GAZETTE [JUNE 
two types when a larger series has been measured, but it is certain 
to be slight. 
Seedlings raised in the laboratory were transferred to the breed- 
ing grounds about June 1, 1913. Typical seedlings of types I and 
If are shown in fig. 5. The cotyledons of type I are somewhat 
Fic. 2.—Type Il, Xanthium pennsylvanicum Wallr.; natural size 
shorter and broader than those of type II, which are long and strap- 
shaped; but the difference is not as great as would have been 
expected from the difference in the seeds. 
The three types were planted within a day of each other; type 
I first, type II the following day, and type III last. As the plants 
