626 EXPERIMENT STATION EECORD. [Vol.41 



3-4, pp. 57-68, figs. 8). — Experiments herein described were suggested by obser- 

 vations reported bj' Brown, both alone and in connection with Worley and 

 with Tinker (E. S. R., 34. p. 626), and his results are said to have been made 

 available at this time on account of the appearance of data contributed by 

 Stiles and Jorgensen (E. S. R., 39, p. 223). Pieces of potato tubers were im- 

 mersed in cane sugar solution and in solutions of mercuric chlorid, osmic acid, 

 mercuric cyanid, or chloroform for different periods of time, and the result- 

 ing data are presented with discussion which is to be continued in a more 

 general form in a later paper. 



The law controlling the quantity of regeneration in the stem of Bryophyl- 

 lum calycinum, J, Loeb (Jour. Gen. Physiol., 1 (1918), No. 1, pp. 81-96, figs. 

 5). — This is in review and continuation of communications previously noted 

 (E. S. R., 40, p. 224). 



A method is noted of measuring the influence of the mass of a leaf of B. 

 calycinum on the quantity of shoots regenerated in an isolated piece of stem. 

 The method consists in isolating a section of stem with only two leaves at the 

 basal node and splitting the stem lengthwise into symmetrical halves, each 

 piece containing one of these leaves, one dormant shoot bud, and two half 

 buds. By reducing the size of one of the sister leaves, the influence of leaf 

 mass on shoot regeneration by the stem can be measured. 



It is stated that the mass of shoots regenerated at the apical bud increases 

 under like conditions and in equal times in proportion to the mass of the leaf, 

 whether the latter be intact or mutilated. The assumption that growth occurs 

 at the expense of the material furnished by the basal leaf is supported by the 

 fact that in the dark the influence of the leaf disappears more or less com- 

 pletely, and that the attached leaf loses greatly in weight. A certain tendency 

 to wilt, ho\^■ever, interferes more or less with the almost perfect proportionality 

 observed under favorable conditions. 



The material furnished by the leaf includes, presumably, both water and 

 solutes. The mass of shoots regenerated by a piece of stem without leaf is so 

 small as to be almost negligible when compared with the mass of shoots pro- 

 duced by a like piece of stem when a leaf of sufficient mass is left attached to 

 its base. 



A consideration of certain pathologic conditions in Ambrosia trifida, A. 

 Stewart (Amer. Joitr. Bot., 6 (1919), No. 1, pp. 84-46, pi. 1, fig. 1).—A further 

 study of the great rag^\'eed A. Mfida (E. S. R., 35, p. 651) in regard to the 

 effects of the disturbance caused by stimuli due to wounding or to attacks by 

 animals or plant parasites, or a combination thereof, is discussed in some detail. 

 It appears that, while wound stimulus is much more powerful than fungus gall 

 stimulus (causing more extensive changes), that due to the presence of the 

 fungus is able to overcome that due to insect attack, when the two occur in the 

 same portion of the plant. 



The nature of charred wood, L. A. Boodle (Roy. Bot. Gard. Keio, Bui. Misc. 

 Inform., No. 9-10 (1917), pp. 306-308).—Notmg the results of experiments 

 bearing upon the nature of the residue of pine or other woods charred by heat 

 or sulphuric acid or both, the author states that a product was obtained by 

 him which differed from typical ch;ircoal in its behavior toward oxidizing 

 agents, a series of degrees of resistance being obtainable evidently bearing n 

 relation to the severity of the charring process. The general conclusion reached 

 is that in certain cases charred wood contains no free carbon unless it is in 

 a condition differing from that of ordinary carbon. 



