924 EXPERIMENT STATION EECORD. 



light, temperature, and water supply. Of these light is often the least im- 

 portant and in many eases is wholly negligible. The other two factors may 

 limit growth ecjually throughout the growing period, or they may in turn be- 

 come the limiting factor according as their intensities vary. 



In these investigations the temperature considered was that of the growing 

 organ itself and not that of the surrounding air. The water-supply factor was 

 found to be very complex and to depend upon absorption and transpiration, 

 which in turn depend updu soil temperature, the water content of the soil, 

 humidity of the atmosphere, and intensity of light. 



In cases of growth without reserve food supply the previous conditions per- 

 tain, but in addition there must be favorable conditions for assimilation and 

 transportation. It is believed that the irregular conditions of growth in the 

 laboratory can be accounted for by the supposition that several different factors 

 upon which growth depends became limiting in turn for shorter or longer 

 periods. In the case of plants under open-air conditions, when all the external 

 factors are liable to variation, it is even more probable that the irregularities 

 of growth curves can be explained in this way. 



Inclosing single plants and its effect on a large number of important 

 agricultural species, C Fruwirth (Aiiicr. Brecdcifi' Asfiov. I'luc, 2 (I'.i06), 

 pp. 197, IDS).- — The object of the experiments which are briefly outlined was to 

 ascertain the effect on seed production of inclosing the entire plant so as to 

 prevent pollen from any other plant reaching it either by means of the wind or 

 insects. The inclosing was done in a number of ways — oiled paper, linen bags, 

 gauze, etc., being used for this purpose. 



It was found that the following plants inclosed in this manner produced 

 ample crops of seeds : Wheat, barley, oats, peas, several species of beans, 

 vetches, camelina, opium poppies, beets, and tobacco. The following gave a 

 greatly reduced quantity of seed: Rye, maize, Vkia faba, hairy vetch, a num- 

 ber of species of Brassica, crimson clover, carrots, timothy, meadow fescue, and 

 meadow foxtail. No fruit or seed was produced from chicory, alfalfa, red 

 clover, white clover, ;ilsike clover, sulla, etc. In the case of sunflowers abun- 

 dant fruits were produced, but the seed was sterile. 



Correlation of characters in plant breeding, II. J. Webher {Amer. Breeders' 

 Assoc. Proc, 2 {1906), pp. 73-S3, pi. 1). — After defining correlations, the author 

 groups them into environmental, morphological, physiological, and coherital 

 correlations. This latter group, which is the most interesting from a scientiflc 

 standpoint as well as from that of practical value, is defined to include those 

 characters which while not related to each other in any direct or casual sense 

 are inherited as a single unit character. A number of correlations of this 

 kind are pointed out in corn, peas, sugar beets, cotton, and other plants. A 

 knowledge of these correlations is very valuable to the breeder, as it will enable 

 judgment to be passed on the probable character of the product while the plants 

 are still young or in their flowering stage. 



The formation and distribution of essential oils in a perennial ]3lant, E. 

 Chararot and G. Laloue {Bid. Soc. Chim. France. .'/. ser., 1-2 (1907), No. 6, 

 pp. 280-290). — The authors report a study made upon the absinthe {Artemisia 

 absinthium) to determine the formation and distribution of the essential oil 

 of that plant. 



Studies were made of plants in all stages of growth, from seedlings to mature 

 individuals, and it was found that the formation of essential oil took place 

 most abundantly just previous to the period of flowering. Following this period 

 there was a diminution in the essential oil. that material ap])arently being 

 used in completing the ripening of the seed. In the roots of the young plants 



