412 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
for flowering plants placed in aseptic conditions to take the nitrogen 
necessary for their sustenance from organic compounds belonging to the 
class of amines in the form of salts. The assimilation of these substances 
may take place without their nitrogen having been first transformed into 
nitric or ammoniacal nitrogen. Ammoniacal salts composed of alkaloids 
cannot supply to plants their necessary nitrogen. Algas placed in 
similar aseptic conditions present the same phenomena as flowering 
plants. Fungi have the power also of deriving their nitrogen from 
amines as well as from nitric or ammoniacal nitrogen. With them, in 
regard both to amines and to alkaloids, the assimilation is in inverse 
proportion to the size of the molecules. 
Influence of Electricity on Plants.* * * § — From a series of experiments 
carried on on a very large number of plants, Mr. G. E. Stone states that 
electricity exerts an appreciable influence on their growth ; the appli- 
cation of certain strengths of current for a short time (one minute or 
less) is sufficient to act as a stimulus. Germination and growth are 
both accelerated by electricity. Electrically stimulated plants do not 
respond immediately, but possess a latent period of about 25 minutes ; 
the excitation produced by alternating currents is more marked than 
that produced by direct currents. 
Herbaceous and Woody Grafts.f — M. L. Daniel distinguishes two 
stages in the anatomical processes which take place in grafting, — the 
preliminary and the definitive stage ; the former lasting up to the 
moment when the functions of the inner and outer generating layers, 
interrupted by the operation, are resumed. The definitive stage may 
again be divided into two periods : — the formation of the cellular tissues 
which fill up the vacancies caused by the wound ; and the differentiation 
of the vessels and sieve-tubes in the healing tissues produced by the 
activity of the inner generating layer, and the formation of bark and 
phelloderm. 
Causes of the Direction of the Lateral Branches of Trees. :£ — 
According to Prof. J. Baranetzky, the development of the lateral 
branches of trees presents two different types. In oue (maple, ash, 
chestnut, &c.) the physiological properties of the lateral branches are 
the same as those of the erect main stem, their oblique direction being 
due to the angle at which they branch from the main stem. In others 
(lime, elm, &c.) the lateral branches are physiologically bilateral even 
in the bud. In pines, all the first year’s shoots are erect. The sub- 
sequent bending down of the lateral branches is due to the unequal 
growth of the tracheids. 
Downward Growth of Rhizomes. § — Herr A. Rimbach attributes 
the power of rhizomes or other underground forms of stem to rise or to 
sink gradually deeper into the soil to changes in the direction of the 
* Bot. Gazette, xxvii. (1899) pp. 123-4. 
f ‘ Bech. anat. s. 1. gretf'es herbacees ct ligneuses,’ Rennes, 1896, 104 pp. and 
3 pl». See Bonnier’s Rev. Ge'u. de But., xi. (1899) p. 78. 
X S.B. Bot. Sect. Naturf.-vers. Kiew, Aug. 28, 1898. See Bot. Centralbl., Ixxvii. 
(1899) p. 108. 
§ Beitr. z. wissenscli. Dot., iii. Abth. 1, 1898, pp. 117-204. See Bot. Centralbl., 
Ixxvii. (1899) p. 25. 
