1917] AGRICULTUBAL BOTANY. 633 



pigment in question occurs in a diffused or finely granulated state in the 

 mitocliondria or the cliloroplusts derived from them, aa a result of a process of 

 crystallization subsequent to such origin, or in diffused granular or crystalline 

 form in the large chromoplasts resulting from the metamorphosis of the chloro- 

 plasts previously formed out of the mitochondria, such mitochondrial origin ex- 

 plaining the elongated early form of the chloroplasts. The formation of vege- 

 table pigments is effected by a process very similar to that v^hich has been 

 recently shown to«occur in the cells of animals. 



The anthocyanin pigments of plants, Mueiel Wheldale (Cambridge: Uni- 

 versity Press, 1916, pp. X-\-S18). — The object of this book is to provide a some- 

 what complete account of the various reports which have been made regarding 

 the anthocyanin pigments as studied along botanical, chemical, and genetical 

 lines. While not claiming that anthocyanins will ever possess great botanical 

 significance, when compared with that of chlorophyll, for example, the author 

 thinks they may develop a wide field for research in connection with problems of 

 inheritance. Owing to the increasing availability of satisfactory methods for 

 the isolation, analysis, and determination of the constitutional formulte of these 

 pigments on the one hand and Mendelian methods for determining inheritance on 

 the other, the two methods combined furnish a reasonable hope that inheritance 

 phenomena may eventually be expressed in terms of chemical composition and 

 structure. 



The eight chapters of the first part deal vdth the anthocyanins as regards 

 their morphological and histological distribution, their properties and reactions, 

 isolation and constitution, physiological conditions, factors, reactions, and sig- 

 nificance. The second part considers the anthocyanins in relation to genetics. 



An extensive bibliography is given. 



Environmental influences on nectar secretion, L. A. Kenoter {Iowa Sta. 

 Research Bui. 37 (1916), pp. 219-232, fig. i).— The results are given of studies 

 of a number of species of flowers, among them varieties of clovers, alfalfas, 

 dandelions, and lilies, to determine the factors which stimulate or retard the 

 secretion of nectar. 



It was found that by increasing humidity, the secretion by the nectaries of 

 water, but not of sugar, was increased. Excessive water supply lessens the 

 sugar surplus, and dilution and washing by rain causes much of the sugar of 

 the nectaries to be lost. The rate of secretion for both sugar and water in- 

 creases with the temperature up to a certain optimum. Accumulation of sugar 

 in the flower varies inversely as the temperature. The optimum condition for 

 sugar secretion was found to be an alternation of low and high temperatures. 

 Variation of atmospheric pressure has no marked influence on secretion. Sugar 

 excretion Is markedly diminished in darkness on account of the limitation of 

 the food reserves of the plant. Water excretion may or may not be limited 

 in this manner, depending on the species. The greatest amount of sugar was 

 found to be secreted under the most favorable conditions for growth and vigor 

 for the plant. Other things being equal, nectar is most abundant early in the 

 blooming season, and the accumulation and secretion of sugar is most pro- 

 nounced near the time of the opening of the flower. 



Environmental influences on nectar secretion, L. A. Kenoter {Bot. Gaz., 

 63 (1917), No. 4, PP- 249-265, fig. 1).— This is essentially the same as the article 

 noted above. 



The consequences of precocity in spring vegetation, 1916, O. Opoix {Compt. 

 Rend. Acad. Agr. France, S {1917), No. 1, pp. 49-52). — Warm weather during 

 nearly all of the winter and spring of 1915-16 resulted In the production of 

 three periods of blooming in apricot trees, occurring about the middle of the 

 months of January, March, and April. A heavy snow February 25 and con- 



