540 EXPERIMENT STATION RECORD. 



tions together with a. list of the officers, referees, and committees of the association 

 for 1905. A previous number of the Record (E. S. R., 16, p. 320) has given a sum- 

 marized account of the proceedings of the association. 



A select bibliography of chemistry, 1492-1902, H. C. Bolton (Smithsn. 

 Misc. Colled., 44, No. 144°, />/'■ ')*>')■ — This is the second supplement to the Select 

 Bibliography of Chemistry and covers the 5 years from 1898 to 1902, inclusive. 



BOTANY. 



Contribution to our knowledge of the development of Prunus americana, 

 R. E. Buchanan {Proc Ioira Acad. Sci., 1!>0.>, />/>. 77-93, ph. 3). — The object of the 

 investigation here reported was to throw light upon the time intervening between 

 pollination and fertilization in the plum. It is commonly believed that although 

 pollen is applied to the pistil and germinates, fertilization and subsequent develop- 

 ment of the embryo is delayed for some time. Other observations were made in 

 connection with pollination, fertilization, and development, the investigations being 

 made with varieties of Americana and the Wild Goose type of plums. 



The author's observations showed that the formation of flowers in the fruit buds 

 began about the middle of July, agreeing in this respect with previous observations 

 made in Wisconsin (E. S. R., 12, p. 22). In normal flowers of most varieties the 

 pistils and stamens are of about the same height, and pollination occurs normally 

 almost immediately upon the opening of the flowers. The fertilization is brought 

 about almost entirely by the common honeybee, although a list of other insect visitors 

 is given. 



The pollen tubes were found to develop very shortly after the application of pollen 

 to the stigma, and the process of fertilization is completed in from one to two weeks. 

 The different members of the genus Prunus have two ovules, only one "of which 

 develops, and until the time of pollination there is no perceptible difference between 

 the ovules. Soon after fertilization one of the ovules gains the ascendency and 

 develops more rapidly than the other, resulting in the finally developed ovule. 



It is a matter of common information that but few plums are produced in compari- 

 son with the number of flowers, and an examination showed that this varied with 

 different varieties, many of the flowers apparently being defective. Self-sterility was 

 found to be very marked in some species, a condition which is not confined to plums 

 alone. This results in a diminished production; and another factor affecting the 

 plum crop is the so-called June drop, which seems to be largely due to infertility. 



A brief bibliography is appended. 



The origin and nature of color in plants, H. Kraemer {Proc. Amer. Phil. Sor., 

 43 {1904), No. 177, pp. 257-277). — After briefly reviewing some of the literature 

 relating to the nature of color in plants, the author divides these colors into two cat- 

 egories, those which are associated with the plastids or organized bodies in the cell, 

 and those wdiich occur in the cell sap or liquids of the cell. The so-called wdnte 

 colors are held to belong to neither class, the white appearance being due to reflected 

 light. 



Microscopical examinations of the different coloring substances did not give satis- 

 factory results, and an attempt was made to consider the behavior of the extracted 

 coloring substances toward chemical reagents. Nearly 100 different plants and parts 

 of plants were investigated, and the reaction toward different chemicals is shown. 



The conclusions of the author are that the white appearance in flowers and other 

 parts of plants is due to the reflection and refraction of light in more or less colorless 

 cells separated usually by large intercellular spaces containing air. The green color 

 of plants is due to chlorophyll contained in the chloroplastids and is more or less 

 constant in all plants. The yellow color substance in roots, flowers, and fruits is due 

 to a pigment to which the author has givei? the name chromophyll In the inner 



