1877.] 215 [Halated. 



Dr. B. Joy Jeffries made some remarks in continuation of 

 his recent communication on color blindness, describing a 

 new test for the discovery of this defect. 



Section of Botany. May 9, 1877. 



Mr. R. W. Greenleaf in the chair. Eighteen persons 

 present. 



Mr. Greenleaf described the structure of the Violet for 

 the prevention of self fertilization. 



Mr. W. P. Wilson showed some forked willow-catkins. 

 He also made some remarks on the germination of Mega- 

 rhiza, a plant remarkable for the extraordinary length of its 

 cotyledonary petioles. 



The following paper was read : — 



Notes upon Vernation. By Byron D. Halsted. 



The leaves of the common lilac (Syringa vulgaris') are arranged in 

 decussating pairs; aDd in the bud each pair encloses all those that 

 are younger — so that the question of vernation is simply the rela- 

 tion of the leaves of any pair to each other. This relation is either 

 one of convolute or imbricate vernation, and always very decidedly 

 one or the other. 



In the following examinations, branches were taken from various 

 shrubs, and six pairs of leaves noted in each of six buds of each branch. 



The buds were examined beginning at the lower end of the 

 branch ; and of course the pairs in each bud in 

 the order of their development. The accompany- 

 ing diagram represents the vernation of the 

 leaves in the six buds of one branch, which was , o c o 



numbered seven; the figures in the side column 

 give the number of the bud, while the upper 

 row of figures designates the number of the pair 



° ° r 5 C C I C C G 



in each bud. Each letter thus represents a pair 6 . 

 of leaves, and where they are convolute the let- 

 ter c is placed, while i is used when imbrication is found. 



