642 APPENDIX. 
numerous that the whole body of the amcebee is filled 
with them; they may be in a perfect state of preserva- 
tion, or quite decolorized, or only recognizable by 
their outline. The amceba rarely contains leucocytes 
or fat-globules. Various forms of bacteria are more 
or less frequent inclusions, and black pigment gran- 
ules and irregular brownish masses of pigment have 
been noted by some observers. 
Biological Characters. The most striking and char- 
acteristic feature of the amceba is its motility. This 
may consist either in an alteration of its shape or in 
an actual change of place. Both of these phenomena 
are produced through the mechanism of pseudopodia. 
These latter are rounded, blunt, and homogeneous 
processes formed by the more or less gradual protru- 
sion of a portion of the ectoplasm at some part of the 
periphery of the ameba. The motion is sometimes 
quite gradual and continuous, at others sudden and 
jerky. The progressive movement—that is, actual loco- 
motion—is brought about by the protrusion of pseudo- 
podia, and into these, when they have reached a certain 
size, the granular or vacuolated entoplasm, with its 
other contents, flows with a more rapid movement 
than that by which the pseudopodia themselves were 
formed. Locomotion is generally observed to take 
place in the direction of least resistance, a group of 
cellular elements or some detritus being sufficient to 
divert the course of the ameba. The ameboid move- 
ments are also influenced by various factors, particu- 
larly by variations of temperature. They are most 
active at the mean temperature of the human body, 
becoming less active as the temperature falls or rises 
above this mean. They become motionless in a tem- 
