138 BOTANICAL GAZETTE [AucUsT 
described as a distinct species, R. Frankii) causes the appearance of 
the threads in a manner already explained. 
The question of Rhizobia species is not yet settled, and cannot 
be settled until our information regarding their biology is much 
more complete. The fact that extensive research work has already 
been done by a large number of investigators without coming to any 
conclusion regarding species should serve as a very suggestive lesson 
Bic. 3-—Portion of longitudinal section of root nodule of beach vetch (Lathyrs 
atid ccctanged Bigel.) showing Injectionsjiden, more abundant in the apical are, 
thizobia are not shown; two starch-bearing cells. 
sil ies hunters. In the case of R. mutabile, the question 1s now 
arising as to whether it is a microbe (Schizomycete) or a hyphal tun 
gus, a question which we hope to discuss more fully in some future 
P ss tae All investigators are agreed that R. mutabile is an organis™ 
showing extreme polymorphism. It would appear to be an 0 
wonderfully adapted to test the De Vriesian theory of mutation as it 
app lies to low organisms. At this time the only statement ven 
. = apparently constant natural variations in R. mutabile, as aN" 
indicated, at once become transformed into “variable or unstable vat 
