1919] AGRICULTURAL BOTANY. 131 



In full light, the principal factor in etiolation is saprophytism. the secondary 

 factors being the iniluence of light, air, and temperature. Bleaching is a result 

 of the formation of formic acid, this phenomenon indicating death, while yel- 

 lowing is characteristic of living plants. 



Studies on the poisonous effects of organic and inorganic acids show that the 

 injury is due to the presence of undissociated acid molecules. 



Yellowing is regarded as of ecological significance. Increase of carbon 

 sources checks chlorophyll formation, and as a result nitrogen may be utilized. 



Controlled pollination In Nicotiana, T. H. Goodspkkd and Pirie Davidson 

 (Unit: Vul. Pubs. Bot., 5 (l'JJS), Ao. 13, pp. 429-434).— The authors indicate the 

 results of controlled pollination experiments carried out with N. langsdorffli 

 grandiflora in a greenhouse, the temperature of which ranged around 30° C. 

 (SU° F. ). While the data are regarded as too fragmentary to justify sweeping 

 conclusions, it appears that fertilization of an extremely small percentage of 

 the ovules is sufficient to prevent abscission of the flower, and it is emphasized 

 that this fact apparently does not depend upon the normality of the embryo 

 sacs and their capability for fertilization. 



It was found that there is in Nicotiana a certain stage of development of the 

 seed capsule beyond which automatic abscission does not occur and spontaneous 

 abscission can not be induced. This is explained by the fact that mechanical 

 tissue is rapidly developed in the pedicel of the flower after anthesis in suffi- 

 cent amount to retain the flower upon the plant. It appears also that no 

 normal pollen is produced by the Fi tabaeum-sylvestris hybrids. Apparently, 

 also, there is no selective fertilization from the point of view of position on the 

 placenta?, the particular embryo sacs reached by the pollen tubes being a mat- 

 ter of chance. 



The inheritance of germinal peculiarities. Flowering 1 plants (Carnegie 

 Inst. Washington Year Book, 16 (1917), pp. 125-127). — An account by the di- 

 rector of the department of experimental evolution is given of Inheritance 

 studies by Blakeslee (E. S. R., 32, p. 72G; 36, p. 522; 37, p. 831), which are 

 being continued. 



In case of the yellow daisy (Rudbeckia hirta), added evidence has been 

 accumulated in regard to the inheritance of self-fertility and self-sterility and 

 the effects of inbreeding. The work on jimson weeds (Datura stramonium) 

 has been extended, and a number of new mutants have been discovered. Results 

 of similar work previously done suggest that the mutant character Is trans- 

 mitted through the female and not through the male parent. In Portulaca a 

 dwarf mutant has been found which appears to act as a Mendelian recessive, 

 but which occasionally produces branches reverting to the normal type, which 

 are heterozygous for the dwarf character. Other vegetative segregations as well 

 as doubling and color types of flowers in this species are being studied. Dou- 

 bling in Portulaca seems to be a Mendelian dominant. Helianthus is under in- 

 vestigation as regards doubling and self-fertility. Verbena is being investigated 

 regarding color characters and self-fertility. The adzuki bean (Phaseolus annu- 

 laris) has been grown for a number of years. Its qualities, some of which are 

 valuable, are discussed. Other studies of adzuki bean and other beans are men- 

 tioned. 



Analysis of a potato hybrid, Solanum fendleriXS. tuberosum ("Sa- 

 linas"), D. T. MacDougal (Carnegie Inst. Washington Year Book, 16 (1917), 

 p. 98). — The wild potato of Arizona (S. fendleri), growing above an elevation of 

 5,000 ft., producing a small tuber, and enduring the climatic extremes of that 

 habitat, has been carried through acclimatization cultures at Tucson and at the 

 Coastal Laboratory. The cross was obtained in 1914 and the second genera- 

 tion, of about 1,000 plants, was brought to maturity in 1917. 



