1 1 2 BOTANICAL GAZETTE [august 



the yeast plant. Growth is usually uniterminal ; again it may 

 proceed in either direction or toward all of the extremities of 

 the branching forms, until the maximum size is reached, where- 

 upon it septates. Under favorable conditions, when food supply 

 is adequate, septation proceeds more rapidly and before the 

 maximum size is attained, forming zoogloea of only partially 

 developed rhizobia. When a fully matured organism septates, 

 the cytoplasm collects into two, more generally three to five, 

 masses, followed by a constriction of the cell-wall between the 

 plasmic masses. Branching forms seem to be due to arrested, 

 prolonged, or incomplete budding, and occur principally in the 

 older, more mature plants, though it may also be noticeable in 

 immature or undeveloped organisms. These peculiarities of form 

 and budding indicate a relationship to Saccharomyces, but there 

 are absolutely no fermentation phenomena in the media. 



In the older, larger, and more matured cells are found those 

 small, usually spheroidal, highly refractive bodies to which 

 attention has been called by various investigators, notably Frank. 

 In the culture organisms, as well as in those found in tubercles, 

 these bodies, which vary in number from one to five, usually 

 occupy a peripheral position. They are highly refractive, in that 

 respect resembling spores. In 1894 I described them as modi- 

 fied spores, an opinion not seconded by Frank (a communica- 

 tion in writing). At present I have nothing to add regarding 

 their origin and probable function, though I am still of the opin- 

 ion that they may be spore-like etiologically, and might be des- 

 ignated sporoids. It seems evident that no true spores are 

 formed, either in the organisms of the tubercles or those grown 

 in media. 



Rhizobium rnutabile grows in most media, liquid beef broth 

 gelatine, agar, beef broth, whether neutral, slightly acid or 

 slightly alkaline. It seems to grow better upon solid than in 

 liquid media. It grows best, as far as observations have been 

 made, upon solid M. alba extract agar. It is not anaerobic, 

 though it may be facultatively so. The fact that the culture 

 is colorless renders the study of deep stab growths difficult, 



