PLATE 13 
A. —Sumac (Rhus glabra). These trees were transplanted in April and remained 
out of doors till September 8, when they were transferred to the greenhouse. They 
received the full seasonal length of day throughout the test. The leaves were shed 
at about the usual time, and the plants remained dormant till spring. Photographed 
January 11. 
B. —Sumac, treated in all respects like the trees in A except that when transferred 
to the greenhouse in September the trees received electric illumination from sunset 
till midnight. The leaves were retained through the winter, and, while growth of 
the original stems was checked, a number of new shoots appeared from the roots 
about January 1. Photographed January 11. 
