DR. DUFFIN, ON PROTOPLASM. 253 
either pass each other or move round each other till, after a 
short interval, each pursues its original course, or the one 
carries the other away with it. They often stop in the midst 
of their career, and then return, but the majority reach the 
extreme ends of the threads, and only then change their 
direction. All the granules of a thread do not move with the 
same velocity, but the one may overtake the other. Where 
several threads coalesce, the granules may be observed to 
pass from the one to the other. As such spots move, ex- 
tensive collections of the material composing the filaments 
may be found, and from these fresh independent processes 
may originate. Many of the granules run evidently quite 
on the surface of the threads, over which they may be dis- 
tinctly seen to project. In addition to the small granules, 
large collections of material resembling spindle-shaped swell- 
ings or lateral intumescences may occasionally be seen 
moving in the same manner as the granules. Even extra- 
neous bodies which may chance to adhere to the filament 
may participate in this movement. 
That this remarkable movement of granules should be 
brought into some relation with the contractility of the sub- 
stance of the pseudopodia has never been questioned, since 
we have no other expression wherewith to designate the 
inner cause of independent animal movement than contract- 
ility. As it is evident that the granules have no active faculty 
of locomotion, but obey the impulses of the basic material, 
this last must of necessity be considered as in a state of 
flowing motion. 
That a filament may lengthen, large masses of substance 
must change their place, and this can often be watched in 
the larger advancing nodules. If this great change in posi- 
tion be admitted for larger portions of the substance of the 
pseudopedia, it is obvious that such a change of locality cannot 
be denied for smaller portions of it. Thus, the expression 
flowing movement of the basic substance is to be explained, 
which, at the same time, gives some indication of the peculiar 
consistence of these contractile pseudopodia which so closely 
resembles that of a fluid. 
Reichert* has objected that in the substance of pseudo- 
podia of the Polythalamiz no granules exist, but that they 
are an optical delusion, derived from waves on the surface of 
the filaments, being mistaken for granules in their substance. 
Against this, Max Schultze argues: 1. The sharp definition 
and decided lustre of the bodies in question do not speak in 
favour of their being only parts of the substance of the 
* ¢ Monatsberichte d. Akad. d. Wiss. zu Berlin,’ pp. 406—426, 1862, 
