74 



The main points in Professor Lloyd's independent conclusions 

 from work on Rubiaceae are : (i) The form of cells in the con- 

 ducti\-e tissue does not determine the course of the pollen-tube, 

 for in RicJiardsufiia and Diodia teres the cells are elongated at 

 right angles to the path of the tube. He believes the chemo- 

 tactic stimulus which determines the direction to be differentially 

 distributed from the egg cell. (2) The ectotropic or endotropic 

 behavior of the pollen-tube is a physiological character. 



The second paper of the evening, by Mr. Edward W. Berry 

 was entitled " Some Monotypic Genera of the Eastern United 

 States and their Ancestors." The phylogeny of Liriodcndron^ 

 was briefly sketched, from its first appearance as a narrow simple- 

 leaved form in the mid-cretaceous of the Atlantic coastal plain, 

 its spread to Europe and Asia, its development into large lobate- 

 leaved forms, and its final extinction except for the existing 

 species of eastern North America and a waning variety in east- 

 ern Asia. Drawings of all the fossil species were shown, and 

 numerous blue-prints of the leaves of the existing species, show- 

 ing their parallelism and range of variation. 



Sassafras was the second genus considered. It was pointed 

 out that while the described fossil species were numerous, many 

 of them arc not allied to Sassafras. The species which were 

 considered as positively identified were discussed, as well as the 

 peculiar characters of the leaves of the existing species, both 

 ancient and modern forms being abundantly illustrated. 



The third genus discussed was Couiptouia. Its former range 

 and development were described and drawings of a number of 

 the species were shown. 



All three genera were considered to have taken their origin 

 from simple-leaved ancestors which flourished during the closing 

 days of the lower cretaceous, and to have originated in America, 

 becoming dominant and widespread in pre-glacial times, finally 

 becoming restricted to their present habitats chiefly through the 

 agency of the glacial conditions of the Pleistocene period. 



The paper was discussed by Professors Rusby, Underwood, 

 and Lloyd and l)i-. llowc. Adjournment followed. 



Tkacv E. Hazen, 

 Secretary pro tern. 



