1»16] AGRICULTUEAL BOTANY. 129 



Three types of commercial vanilla in Tahiti, Costantin and Bois (Compt. 

 Rend. Acad. Sci. {Paris], 161 {1915), No. 8, pp. 1^6-202).— Discussing three 

 types of vanilla in Tahiti, the authors state that the tj'pe called Mexican vanilla 

 is V. planifolia, that the type called Tahitan vanilla is closely related thereto, 

 but that the type which has been provisionally called V. tiarei, and which is 

 thought to have appeared there Ave or six years ago from an unknown source, 

 may be a variation or a hybrid. It is said to possess qualities of commercial 

 value. 



Quichua names of sweet potatoes, O. F, Cook {Jour. Wash. Acad. Sci., 6 

 {1916), No. /f, pp. 86-90). — The author gives some results of studies carried out 

 by himself as a member of the Yale Peruvian Expedition, conducted by Prof. H. 

 Bingham in cooperation with the National Geographic Society and the U. S. 

 Department of Agrictulture. 



It is stated that the Quichas, who live on the eastern slopes of the Andes, use 

 and have used apparently from antiquity the names " apichu " for the sweet 

 varieties of Ipomoea batatas and " cumara " for the starchy kinds, the inclusive 

 term " camote " being used for both kinds by those who speak Spanish. Both 

 these varieties are represented by local strains having local names, a number of 

 which are given. Wild sweet potatoes are also said to be common in the val- 

 leys of the interior. 



It is stated that, while among all the native names used in other parts of 

 America tliere appears to be no definite resemblance to the Quichua words 

 " apichu " and " cumara," the number and variety of such names testify to the 

 American origin of the sweet potato, or at least to its wide distribution in pre- 

 historic times. The name " cumara," or " kumara," is also used for the sweet 

 potato in Polynesia. This fact is regarded as more than a mere coincidence. 



Physico-chemical studies in botany. — I, Germination, Helene Nothmann- 

 ZucKEKKANDL {Intcrnat. Ztschr. Phys. Chevi. Biol., 2 {1915), No. 2-3, pp. 9^- 

 106). — This is a review of the results and conclusions published by previous 

 investigators on germination. 



The germination, xinder aseptic conditions, of Zea mays in the presence of 

 some quinonoids, D. Roudsky {Compt. Rend. Soc. Biol. [Paris], 77 {1914), No. 

 20, pp. 30-33. fig. 1). — Describing the behavior of maize seedlings grown by 

 placing sterilized seeds on cotton in test tubes, the author notes that, while in 

 case of the control tubes containing water only the roots penetrated the liquid 

 freely and atttaiued considerable development, in tubes containing a dilute 

 solution of an azin, a diamidoacridin, or one of two oxazins, the roots failed 

 to descend into the solution, a portion of the rootlet showing also a certain 

 coloration extending to the growing part. The lowering of the liquid surface 

 of the solution due to evaporation was followed by renewed growth of the root- 

 let, in some cases carrying its point into the liquid, this fact suggesting a degree 

 of adaptation to a medium which at first appeared to inhibit growth. 



Light and growth, II, A. H. Blaauw {Ztschr. Bot., 7 {1915), No. 8, pp. 465- 

 532, figs. 10). — The author has followed up his work previously reported (E. S. 

 R., 34, p. 223) with studies on plantlets of Helianthus globosus as regards rate 

 of growth and response to illumination of various intensities and durations. 



It is held that in multicellular organisms a characteristic growth reaction 

 is produced which is due to physico-chemical change. Phototropism is a sec- 

 ondary phenomenon of the growth reaction to light which results when the plant 

 is subjected to unequal illumination on different sides. Plant cells are not 

 stimulated because of obliquity of light or of unequal intensity thereof on dif- 

 ferent sides. There is no perception of light or of differences of illumination, 

 but light produces alterations in growth rate which may quickly manifest 

 themselves through a striking response. 



