1919 J AGRICULTURAL BOTANY. 223 



293). — The author reaches the conclusion that the increased dry weight of 

 A. niger occurring in cultures growing in Jena flasks is due to the solution of 

 small amounts of zinc from the material of the flasks. 



The nature of the chondriome and its role in the cell, P. A. Dangeabd 

 (Compt. Rend. Acad. Sci. [Paris], 166 {1918), No. 11, pp. 439-446, figs. 4).— The 

 author undertakes to make clear the nature and functions of certain intracel- 

 lular elements, each alleged to belong to either, but not to both, of two systems 

 which are claimed to be wholly distinct and which are here described and 

 designated by the general names plastidome and chondriome. These two sys- 

 tems are said to be often confused in contributions dealing with the micro- 

 structures, microactivities, and microtechnique of cells. 



Intramicrosporangial development of the tube in the microspore of Pinus 

 sylvestris, L. H. Harvey (Ann. Rpt. Mich. Acad. Sci., 19 (1911), pp. 333-335, 

 figs. 2). — Observations of material collected in May, 1910, from an exposed tree 

 60 or 70 years old are noted. One or two per cent of the microspores examined 

 showed pollen-tube development, two tubes in several cases arising at opposite 

 poles of the microspore. It has been assumed that the tube development here 

 recorded was a chemotropic response to the stimulus arising from a mucilagi- 

 nous substance secreted by the nucellus (the so-called pollination-drop) or from 

 contact with the nucellus. However, it is here maintained that the chemo- 

 tropic stimulus of the nucellus is not essential to the development of the 

 pollen tube in P. sylvestris. 



Further results in desiccation and respiration of Echinocactus, E. R. Loxo 

 (Bot. Gas., 65 (1918), No. 4, pp. 351,-358, fig. 1 ) .— Continuing work previously 

 noted from another source (E. S. R., 40, p. 29), an Echinocactus, which had 

 been loaded with carbohydrate by desiccation for eight months in the open, 

 was placed in a ventilated dark chamber where katabolism would go on without 

 extensive repair, and the course of resulting changes occurring during 2$ years 

 are given herein. 



The rate of water loss was remarkably uniform, being almost independent 

 of seasonal changes. Several distinct changes in the sugar concentration are 

 noted. Soluble sugars appear to have been largely destroyed, though destruc- 

 tion of stored insoluble polysaccharids seems to have been hardly more than 

 begun. Other changes are noted with discussion. The breaking up of the 

 stored insoluble polysaccharids apparently proceeds very slowly, and this fact, 

 taken in conjunction with that of the resistance of Echinocacti to desiccation, 

 is supposed to explain partly the viability of these plants in spite of prolonged 

 starvation. 



Determination of acidity in plant tissues, H. M. Richards (Mem. Torrey 

 Bot. Club, 11 (1918), pp. 241-245 ).— Discussing the methods of obtaining plant 

 juices for titration and some of the disadvantages of such methods, the author 

 claims to have found that what appears to be a very close approximation of a 

 total acid content may be obtained by repeated pressure. 



Dynamic aspects of photosynthesis, W. J. V. Osterhout and A. R. C. Haas 

 (Proc. Nat. Acad. Sci., 4 (1918), No. 4. pp. 85-91).— The authors, noting means 

 employed to lessen temperature fluctuations in this work, describe in this 

 preliminary communication their studies carried out with Ulva rigida and .it her 

 materials. 



It is stated that Ulva, after having been kept in the dark, sets up photo- 

 synthesis as soon as exposed to light, the rate steadily increasing until a con- 

 stant speed is attained. An explanation is offered, and quantitative theories 

 are developed to account for the facts observed. 



Effects of rest and no rest periods upon growth of Solanum, W. F. Gericke 

 (Bot. Gas., 65 (1918), No. 4, pp. 344-353).— In a study of rest periods carried 



