450 SUMMARY OF CURRENT RESEARCHES RELATING TO 



reagents which ho made in order to ascertain the structure of the hairs, 

 and the nature of the secretion. 



Formation of Roots in Loranthacese.*— Dr. C. v. Tubeuf has ex- 

 amined the structure and mode of formation of the roots in several 

 exotic species of Loranthacese, viz. -.—Areeuthobium Douglasii, parasitic 

 on Pseudotsuga Douglasii, and A. americanum on Finns Murrayana in 

 America ; Viscum Kaempferi on Pinus densiflora in Japan ; V. articulatum 

 on Ligustrum japonicum, and Loranthus longiflorus from India. 



The species of Areeuthobium have cortical roots, with layers, but with- 

 out the regularity of structure and arrangement of the layers on the 

 cortical roots of the mistletoe. They cause not only a hypertrophy, but 

 also a " witch-broom " formation, which is exceedingly destructive to the 

 Douglas pine. Viscum articulatum has only a single root-disc, which 

 grows in the cambium region of the host, interposing like a shell 

 between the wood and the bast. V. Kaempferi and Loranthus longijlomn 

 twine round the host, and put out roots which penetrate the bark into 

 the wood. Loranthus has only a single growing point to the root, while 

 the root of V. Kaempferi branches in the cambium region of the host like 

 a many-fingered hand. The roots grow with great rapidity, spreading 

 over a large space of wood in the course of a year, and putting out 

 numerous lateral branches, which penetrate successively into all the 

 subsequent annual rings of wood. 



Root-hairs of the Rhinanthese.t— M. Leclerc du Sablon, having ex- 

 amined the roots of 3Ielampyrum pratense, which have been developed in 

 a humid atmosphere, determined the existence of numerous hairs of very 

 different dimensions ; some the length of ordinary root-hairs, others 

 much shorter, others again developed as small papillte. In Melampyrum 

 the parasitism has not done away with the normal organs of absorption. 



Mycodomatia in the Roots of Papilionacese.J — Herr A. N. Lund- 

 strom accepts generally Woronin's interpretation of the swellings on the 

 roots of Papilionacese, that they are caused by substances of a fungoid 

 nature, which develope a kind of symbiosis advantageous to the plant in 

 causing these structures to become reservoirs of food material. The 

 tendency to produce these structures may, he thinks, become hereditary. 



In specimens examined of Trifolium repens, he finds in the cells large 

 numbers of active " bacteroids " ; the number of these and the quantity 

 of starch in the cell appear to be in inverse proportion to one another. 

 They seem, in fact, to derive their sustenance from the starch-grains. 

 The bacteroids are very transparent, not refringent, and are coloured a 

 light yellow by chlor-zinc-iodide. The author considers that their very 

 active movements cannot be due to molecular motion. They vary greatly 

 in size, and become gradually more and more granular. Attempts to 

 produce germination had negative results. 



Morphology of Underground Stems.§ — According to a number of 

 observations made by Herr T. Bruck on both Monocotyledons and 



* Bot. Ver. Miinchen, March 21, 1887. See Bot. Centralbl., xxxiii. (1888) 

 p. 346. 



t Bull. Soc. Bot. France, xxxv. (1888) pp. 81-2. Cf. this Journal, ante, p. 250. 



X Naturv. Studentb'allsk. Upsala, April 28, 1887. See Bot. Centralbl., xxxiii. 

 (1888) pp. 159 and 185 (1 pi.). Cf. this Journal, ante, p. 251. 



§ Progr. d. griech.-oriental. Ober-Realschule in Czernowitz, 1885, 14 pp. and 

 5 pis. See Bot. Centralbl., xxxiii. (1888) p. 168. 



