SHREVE 



PLATE 1 



A. Parkinsonia microphylla, end branch of a tree. 



B. Plants of Parkinsonia used in experiments VI-X. Counting from left to right, Nos. 1 -3 were raised 



in the green-house, Nos. 4-5 were grown under natural conditions having been transplanted to pot$ 

 a short time before the experiments. Nos. 1 -4 are one year old. No 5 is about eight years old. 



C. Parkinsonia microphylla, adult tree. 



