(gor] CURRENT LITERATURE 375 
tion, and come to occupy a position at the poles of the nuclear spindle. He 
regards them as undoubtedly centrosomes.— J. M. C. 
Miss MARIA Dawson reports the results of three years’ experimentation 
to determine the economic importance of nitragin, the commercial culture of 
the nodule organisms of Leguminosae. Her conclusion is “that for peas 
grown upon ordinary garden soil, peat, clay, or loam inoculation with nitragin 
is useless and superfluous, whilst upon gravelly soils a small increase in crop 
results from its use.” *3—C R.B 
ELIZABETH DALE“ has studied the aerial tubers which are often very 
prominent in species of Dioscorea, notably D. safiva, in which they are said 
to become six or more inches in diameter. A study of their origin seems to 
indicate that they are stem structures, with conspicuous powers of propaga- 
tion. In fact, the author ventures the statement that ‘‘the abundant forma- 
tion of auxiliary tubers in m many species of Dioscorea seems as if it were 
connected with the fact that these plants do not appear to form seed 
readily,’’— C: 
DUusEN has studied the byrological collections of the Swedish polar expe- 
dition under Dr. A. G. Nathorst in 1899. The localities visited on east 
Greenland extend from Pendulum island (74° 40’ N.) to Cape Stewart (70° 
30’ N.), about 150 miles north and south of Cape Parry. The island of Jan 
Mayen was also visited. In this work he has had the assistance of Dr. H. W. 
Arnell on Bryum and Plagiobryum, and of Herr C. Jensen on Dicranum and 
Sphagnum. Bryum subnitidulum, B. Dusenii, B. minus, B. Groenlandicum 
and B. Jan Mayense are described by Arnell as new species, and the sporo- 
phyte of B. obtustfolium is fully described for the first time.*—C. R. B. 
WAS OBSERVED by Sachs that when orthotropous roots, not too young, 
are inverted, they do not return to the vertical but become plagiotropous. 
émec finds a satisfactory explanation * of this in the alteration of the recep- 
tive apparatus described in his previous paper,” thus confirming his views as 
to the nature of the perceptivity of typical roots, as well as Noll’s idea, arrived 
at from theoretical considerations, that alterations in the response to directive 
Stimuli have their source in an alteration of the receptive structure. He has 
observed, coincident with this induced plagiotropism, a change in the “— 
8raphic relations of the quality of the sensitive plasmic layer. The differ- 
ence between the original and the newly assumed structure is just the 
egy of Botany 15: 511-519. 1901. 
n the origin, development, and —_— nature of the aerial tubers in 
pha sativa. Ann. of Bot. 15: 491-501. p/. 26. 190 
*5 Bihang till Svenska Vet. Akad. Handl. 27: 1-71. pls. g. 1901. 
** Berichte deutsch. bot. Gesells. 19: 310-313. 1901. 
*7 Jahrb, £. wiss. Bot. 36:80. 1901. See also Bot. GAZ. 32: 145. 1901. 
