| 784 The American Naturalist. [September, 
that infection takes place by means of the “Infektionsfaden.” 
This seems improbable since the “Infektionsfiiden” are not 
always present. I could find no trace of them in Phaseolus 
vulgaris. They are sometimes present in Trifolium pratense. I 
have been unable to find them in Robinia pseudacacia, although 
Moeller states that they are present. In all those cases in 
which I found them I could detect no connection between them 
and the Rhizobia. They are sometimes found in tissues out- 
side of the tubercle having no apparent connection with it. 
In chemical behavior and microscopical appearance the 
“Infektionsfiiden” differ considerably from the Rhizobia. The 
“Infektionsfiden” consist of a more highly refractive albumin- 
oid substance and stain less readily than the Rhizobia. Ihave 
often found them in old tubercles of Trifolium pratense in 
whieh the Rhizobia and cell protoplasm had been almost 
wholly removed showing thatthey have a greater vitality than 
either the plant cell or the Rhizobia. Heretofore no one has 
been able to detect a membrane on the *Infektionsfüden." 
Recently Moeller’ has announced the discovery of a cellulose 
membrane surrounding the “Bacteria zoogles"—" Infektions- 
fáden." This membrane, he asserts, is secreted by the cell pro- 
toplasm as a protection against the intruding bacteria (Rhizo- 
bia). In the same article Moeller notes that the bacteria 
(Rhizobia) have the power to dissolve cellulose. These state- . 
ments are certainly a little difficult to understand. It would 
seem improbable that the bacteria (Rhizobia) should at one 
and the same time dissolve cellulose and also have a coating 
of it deposited on them as a protection against their intrusion. 
It is known that eggs of parasites, larvæ in the resting stage, 
calcium oxalate crystals, etc., when found in plant tissues have 
had secreted around them a coating of cellulose. In such 
cases, however, the foreign substance does not at the same time 
have the power of dissolving cellulose. 
Without going into further discussion, it is known that the 
Rhizobia gain access to the interior of the surface root-cells 
where they multiply rapidly. By their irritating presence, 
inereased protoplasmic action takes place. Not only do the 
t Bex. der deutscb. bot. Ges., Heft 5, 1892. 
