188 The American Naturalist. [September, 
bodies are readily stained with iodine solution, but while Frank 
notes a reddish brown stain Moeller affirms the color to be 
dark brown. I have noted similar highly refractive bodies in 
Ehizobium mutabile of Melilotus alba, Trifolium pratense, Trifol- 
ium repens, and Lathyrus odoratus but not in Phaseolus vulgaris, 
or Pisum sativum. These two last named plants are infected 
by Rhizobium Frankii var. major and minor respectively. So 
far I have only found these bodies in Rhizobium mutabile. 
These bodies are, as before stated, highly refractive; generally 
rounded, and may be located in the centre or toward the peri- 
phery of the usually more or less modified Rhizobium. I have 
been unable to stain them with tincture of iodine. Fuschin 
stains them with difficulty. The various aniline dyes have 
practically no effect upon them. As to their chemical nature 
I am not prepared to express a definite opinion. Iam of the 
opinion that they are not starch. I am more inclined to 
Moeller's view that they are due to a fatty degeneration of 
protoplasm in improperly nourished Rhizobia. This. would 
especially be expected in mature degenerating tubercles, which 
are the only ones that contain the Rhizobia with refractive 
bodies. Fatty degeneration is quite common in animal proto- 
plasm. It sometimes happens that a starch granule is deposi- 
ted inside of the partially or wholly empty case of a Rhizo- 
bium. This however is purely accidental and does not occur 
often. Of course such Rhizobia will contain highly refractive 
bodies that stain readily with iodine. 
The greatest changes take place in the infected area of the 
tubercle. Here everything points to increased protoplasmic 
activity. The cells grow and multiply rapidly, they are 
entirely filled with a mixture of Rhizobia and protoplasm and 
in some cases the “ Infektionsfdiden.” The nuclei are abnor- 
mally large, the nucleoli become more distinct. All the 
different cell elements stain much more heavily than those of 
the normal cell. In Phaseolus vulgaris the nuclei becomes very 
much modified, they increase in size, the nuclear wall thick- 
ens, sooner or later the weaker spots of the wall give way and 
allow the nucleoplasm to protrude giving the whole an amoeba 
like appearance. Finally the nuclear wall ruptures on one side 
