No. 389.] REVIEWS OF RECENT LITERATURE. 451 
Brunchorst recently renamed Frankia subtilis. Frank regarded the 
peculiar cells always found in these tubercles as bodies of fungus 
origin, which had degenerated because of their mode of life within 
the cells of another plant. Moeller, on the other hand, regarded 
them as single-celled Hyphomycetes. From an extended series of 
experiments Hiltner’ comes to the conclusion that Frankia subtilis 
is not a single-celled Hyphomycete, but a bacterial organism which 
possesses sporangia, and because of these and other peculiarities 
forms a connecting link between the bacteria and the true fungi. He 
succeeded in inoculating the organisms into roots of alder seedlings 
grown in N.-free nutritive solutions. The organisms enter through 
the root hairs in a manner similar to that of the organism causing 
leguminous tubercles. Inside of each hair is a mucilaginous thread 
in which the bacteria lie imbedded without any system or regularity. 
Before reaching the root proper the mucilaginous mass becomes fila- 
mentous and resembles mycelial threads. Within the root the muci- 
lage masses resemble plasmodia, which extend from cell to cell, and 
ultimately become of a spongy consistency because of the appear- 
ance of numerous vacuoles, surrounded by thin walls of mucilage, in 
which the bacteria, now more or less in thread form, lie. Very soon 
after the formation of a tubercle the individual bacteria change into 
spheres filled with albumen, which rapidly differentiates into spores ; 
in other words, the spheres represent sporangia. ‘The spores germi- 
nate rapidly, forming short rods which fill the cells of the tubercle 
but develop no mucilage. Hiltner points out that, with the exception 
of Bacillus erythrosporus, few bacteria form sporangia. According to 
his view, the bacteroids of the leguminous tubercles must be regarded 
as sporangia, and in that case the bacteria of the alder and Legumi- 
nosæ, both forming plasmodia, constitute a new group of bacteria. 
Numerous experiments have proven the fact that the organisms in 
the alder tubercles are capable of fixing atmospheric nitrogen; and, 
unlike those of the Leguminosz, they are able to function fully under 
water. We are promised a full exposition of the subject in another 
journal at no distant date. HERMANN VON SCHRENK. 
The Red and Blue Coloring Matters of Flowers are discussed 
in Natural Science for February, by P. Q. Keegan, in continuation of 
a paper published in the same journal of December last. In view of 
1 Hiltner, L. On the Origin and Physiological Significance of Root-Tubercles. 
B. The Root-Tubercles of the Alders and Eleagnacex, Forstlich Naturwissensch. 
Zeitschr., Bd. vii, p. 415, 1898. 
