218 BOTANICAL GAZETTE | MARCH 
Miss Marta Dawson has studied the tubercle organism and the mode of 
infection in Vicia hirsuta and Pisum sativum.’ Her results confirm those of 
previous observers as to the mode of infection by tubes traversing one or more 
root hairs into the cortex. These tubes have the advancing end open and 
consist of numbers of straight rodlets with longer axes arallel to the line of 
growth of the tube. Finally, after traversing a cell, the tube bursts on one 
side and sets free the rodlets in the cell cavity. (No such infection tubes 
were found in Lupinus and Phaseolus.) e matrix enclosing the rodlets 
contains nothing of the nature of cellulose or chitin, or (probably) mucilage. 
ese characters are conclusive against the organism being one of the true 
fungi, and call to mind Prazmowski’s view that it is a filamentous zooglcea form 
of a schizomycete, and also Thaxter’s Myxobacteriacee. Drop-culture experi- 
ments, the first of the kind, enabled the author to follow the multiplication of 
the rodlets by constriction and separation, the process being completed in 
2-4 hours. Bacteroids were also developed in these cultures, but the author 
has not yet been able to observe the process of their development. Experi- 
ments were also made with “nitragin,” which showed that it contained the 
tubercle organism and induced tubercle formation by direct application to 
seeds or through the soil.— C. R. B. 
IN THE Journa/ of the Cincinnati Society of Natural History (19: 147-166. 
4 Jan. 1900) Dr. A. P. Morgan publishes his fifth paper on the Myxomy- 
cetes of the Miami valley, Ohio, in which he presents various systems of 
classification of this group, some of them of only historical interest. The 
paper closes with his own grouping of the genera of North America, under 
four sections, with analytic keys to the genera.— C. R. B 
No boust students of histology will be interested in hearing how, accord- 
ing to the editor of Meehan’s Monthly, trees increase in diameter. Explaining 
how a label was overgrown instead of being pushed outward he writes: ‘To 
those who understand the manner in which new wood forms, the explanation 
is simple. The increase in the girth of trees takes place during a few weeks 
at midsummer, and is by the rapid multiplication of minute cells. These, 
at first, are as soft as mush, and might be compared to the flow of so much 
yeast. If the flow is checked in one direction, it turns to the direction its 
neighbor is journeying, and adds itself to the volume of that stream.” The 
persistence of erroneous ideas is amazing.—C. R 
STUDENTS of grasses will hardly look for articles on that group in me 
Revue Bryologique. Yet the opening number for Igoo contains two by X. 
Orzeszko of Nice; one on the processes for securing good sections of dried 
leaves of grasses, ¢. ¢:, for histological study of herbarium material, and @ 
second consisting of an elaborate code of signs for histological description of 
* Phil. Trans. Roy. Soc. London B. 192: I-28. 1899. 
