AGRICULTURAL BOTANY. 627 



host plant by circuinnutatiou, it turns back upon itself. Although not affected 

 by contact with itself while the host was available, the shoot now readily 

 responds to the stimulus of this contact, twines around its own lower portion, 

 and produces haustoria which absorb nutriment therefrom. Field and labora- 

 tory studies show that a physiological connection is established in such cases. 



It appears to the author that in this way the spreading or nutating shoot 

 escapes death from starvation, and by retracing its course is enabled to reach 

 a fresh portion of the host or to find a new one. 



This is considered as a notable addition to the facts existing in favor of the 

 theory that the haustoria are new formations produced for a special purpose. 



Oxidation of ammonia or nitrification in plants, P. MAzfi (Conipt. Rend. 

 8oc. Biol. [Paris], 78 (1915), No. 5, pp. 98-102).— The author has followed up 

 his previous observations regarding the presence of nitrous acid in water 

 exuded from plants (E. S. R., 28, p. 429) with a study of maize, pea, and 

 vetch in this connection. 



It was found that plants kept at a temperature of 30° C. produced no nitrous 

 acid, while a certain amount was formed by those kept at 56 to 57°. 



It is thought that the formation of nitrous acid is the resultant of two 

 opposed processes, the temperature of 56 to 57° having a tendency to check 

 reduction more than oxidation, and the conditions produced by the immersion 

 of the plants in water appearing to be unfavorable to the oxidizing action. 



A study of nitrogen release by Azotobacter, T. ]Mol6b [Bot. Notiser, No. 

 If {1915), pp. 163-178, pi. 1, fig. 1). — The author has devised and employed a 

 culture filter apparatus which is said to permit of the removal and separate 

 examination of metabolic products from bacterial cultures. 



It is stated that A. chroococcnm during its life separates no soluble nitrogen 

 compounds, but only after death furnishes nitrogen to higher organisms. Star- 

 vation brings this organism into a resting condition. 



Proteolytic bacterial enzyms are entirely ineffective toward the nitrogenoiis 

 compounds contained in this organism. The presence of such compounds in 

 cultures is to be explained as due probably to the activities of amoebse which 

 use it for food. 



A. agile and A. tcienlandii behave in a different way, both separating soluble 

 nitrogen compounds. 



Carotinoids in plants, C. van Wisselingh (Flora, n. ser., 7 (1915), No. Jt, 

 pp. 371-432). — Describing the methods and results of his examination of a 

 large number of plants, the author states that he has been able to demonstrate 

 in a number (which are listed) the presence of two or more carotinoids. 



The mode of formation of starch, in rootlets of maize and castor oil plant, 

 A, GuiLLiERMOND (Arch. Anat. Micros., 16 (1915), No. 3-5, pp. 5^9-554, pi- 1). — 

 The author calls attention to an error (due to wrong labeling of material) 

 which he has discovered in his statement of observations as previously noted 

 (E. S. R., 28, p. 524). This is said, however, not to modify the general results 

 and their interpretations. 



The growth, of the leaf blade, leaf sheath, and stalk of the sugar cane, 

 J. KuYPEE (Meded. Proefstat. Java-Siiikeri7idus., 5 (1915), No. 8, pp. 211-239, 

 figs. 6). — The author has devised a method of measuring the growth of the 

 younger portions of the sugar cane plant occurring while these are still invisible 

 from the outside. 



Small holes were made with a needle at regular intervals entirely through 

 the bundle of growing parts. On removal of the successive layers some days 

 thereafter, the amount of growth could be determined. The results as regards 

 growth are shown graphically for the several portions. The region of most 



