154 Proceedings of the Itoijal Physical Society. 
grouped together ; while in others again, as many as nine or 
ten are detected in two clusters (fig. 2) ; but in these cases 
I am disposed to think that the individual is composed of two 
animals in a state of conjugation, as it is always elongated 
and slightly constructed between the masses of nuclei. 
These animals, from their large size (from Jth to Jth of an 
inch in diameter), can be readily transferred to a flat cell 
under the microscope, when the excessively rapid movement 
of the sarcode affords a very interesting and astonishing 
spectacle. Each of the great pseudopodia consists of a 
number of streams, some rapidly coursing outwards, others 
passing inwards more slowly, and dragging along masses of 
diatoms, minute alga, and infusoria. Even in the most 
minute branches of the periphery a double movement, in 
opposite directions, is clearly visible under high amplifica- 
tion. In fact, the whole organism reminds one of a great 
central railway station, the meeting-point of numerous con- 
verging lines, to which an unceasing flow of traffic is ever 
tending. A rude touch, as with a needle point, to the animal 
itself, has the effect of arresting the outward movement, 
and of determining the whole flow rapidly to the centre. 
An explanation of the movements of the pseudopodia is 
extremely difficult ; and indeed the same may be said of 
the nature of the pseudopodia and whole structure of the 
rhizopod itself. We find it difficult to believe that a mere 
mass of gelatinous slime, apparently homogeneous, can 
determine such purpose-like and varied movements through 
the wide-spread and ever varying extension of its network, 
and can instantly arrest or alter these movements at will, or 
from the effect of external stimulus. Accordingly, Eeichert 
has dissented from the sarcode theory, first promulgated by 
Dujardin and strongly insisted on by Schultze, and is of 
opinion that the pseudopodia consists of bundles of exces- 
sively fine filaments — so fine " that a perceptible thickening 
scarcely appears when several filaments come together, or 
when the magnifying power is raised from 450 to 700 
diameters.'' He considers that when the animal first ex- 
tends its pseudopodia the more simple radiate arrangement 
predominates ; soon afterwards the apparent ramifications 
