PEOTOPLASMIC MOVEMENT. 381 



colourless blood-corpuscle of a frog assumed at intervals of 

 one minute. 



The Plasmodium of Myxomycetes is very good for the 

 study of amoeboid movement, on account of the great size of 

 the protoplasmic masses and the extreme rapidity of the move- 

 ments, which are visible even to the naked eye. The processes 

 here run together in networks, which may cover more than 

 four square centimetres. 



A. De Bary ^ describes the movements thus : — " There are 

 two varieties. In the first place, in every mass of transparent 

 Plasmodium a large number of granules are to be seen in active 

 streaming. In all the thread-shaped branches there is always 

 one current only along the axis of the branch ; where branch- 

 ing takes place the current divides, following the branches, or 

 if the movement is taking place in the other direction the 

 currents in the branches flow together into the main stream ; 

 not unfrequently, however, the streaming proceeds in one 

 lateral branch only, while in the other no movement, or one 

 in the opposite direction, prevails. 



" In smooth, skin-like expanses numerous branching streams 

 generally run either in the same or in different directions, and 

 often streams going in directly opposite directions run side by 

 side. 



" The peripheral substance, within which the granulated pro- 

 toplasm streams, exhibits a movement which appears for the 

 most part unconnected with this, and which consists in a 

 slow flowing or undulating change of the margin, small pro- 

 cesses being continually extruded and withdrawn again. The 

 granules are often quite unaffected by these movements, but 

 sometimes are carried in smaller or larger numbers into the 

 small tentacle-like branches. The activity of the peripheral 

 movements varies much, under continued observation. Very 

 trifling changes in the margin are to be seen, and the flat 

 expanses in particular often look like a perfectly still sur- 

 face sprinkled with motionless granules while the streams flow 

 through it. 



1 A. De Bary, 'Die Mjcetozoen.,' 2 Aufl., p. 43, et seq., Lepzig, 1864. 



