478 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Symbiosis of Algae and Bacteria with Cycas.* * * § — Mr. A. Schneider 
states that the roots of Cycas revoluta are constantly furnished with 
tubercle-like growths, the palisade-layer of which is commonly infested 
with a Nostoc. The alga is certainly not the cause of the develop- 
ment of the tubercle, and it appears not to be harmful to the host. 
Nearly all the cells of the tubercle also contain bacteria and rhizobes, 
among which were detected a coccus, and two rhizobes resembling 
1 Ihizobium Franldi and It. mutabile. 
Life-history of the Mistletoe.' f — According to M. C. Guerin, the 
slime of the mistletoe-berry serves no purpose in glueing the berry to 
the branch, its function being the absorption of water ; propagation is 
effected almost entirely by insectivorous birds, and especially by the 
missel-thrush, on which it has a purgative effect. Freezing does not 
destroy the germinating power of the berries. The seeds germinate 
only in the light ; the branches are at first negatively geotropic ; but 
afterwards grow straight. The majority of the seeds contain more than 
one embryo. The author was able to make the mistletoe grow parasiti- 
cally on itself, although this does not occur in nature. Even in winter 
the parasite, and especially the male plant, absorbs a considerable amount 
of moisture from the host. The structure of the bark of the host is an 
important condition in the germination of the mistletoe, and this may 
account for its comparative rarity on the pear. 
Assimilation of Nitrogen by Plants. — A further series of experi- 
ments on this subject carried on by M. E. Breal % show that the soils of 
forests and natural prairies are highly charged with organic matter, 
forming a medium in which the nitric ferments cannot transform ammonia 
into nitrate, and the vegetation is obliged to assimilate nitrogen in the 
form of ammonia. Grass land, therefore, becomes rich in organic 
nitrogen, in consequence of the small amount of nitrification which takes 
place. 
Further experiments by M. S. Winogradsky § show that the absorption 
of free nitrogen by bacilli, which he has already demonstrated, is due 
to the contact of the gas which they give off in the fermenting process 
with nascent hydrogen within the living protoplasm ; the result being 
that ammonia is formed. 
According to Herr G. Liebscher,|| experiments on peas, oats, buck- 
wheat, and mustard establish that there is only a difference in degree 
between the nitrogen-fixing power of the Leguminosse and that of other 
plants. 
Experiments by Herr J. B. Lotsy^f on black and white mustard 
showed that neither is able to live in the absence of combined nitrogen. 
Prof. H. Marshall Ward ** gives a very useful summary of recent 
* Bot. Gazette, xix. (1894) pp. 25-32 (2 pis.). 
f Bull. Soc. Linn. Normandie, vi. pp. 183-229. See Bot. Centralbl., 1894, Beih., 
p. 30. 
x Ann. Agron., xix. pp. 274-93. See Journ. Chem. Soc., 1893, Abstr., p. 590. 
Cf. this Journal, 1893, p. 357. 
§ Comptes Rendus, cxviii. (1894) pp. 353-5. Cf. this Journal, ante, p. 97. 
|| Journ. Landw., xli. pp. 139-98. See Journ. Chem. Soc., 1894, Abstr., p. 201. 
Exp. Stat. Bull., 1894, No. 18. See Journ. Chem. Soc., 1894, Abstr., p. 205. 
** Nature, xlix. (1894) pp. 511-4. 
