236 E. RAY LANKESTER. 
aud outstretched system of threads suddenly contracts, and 
forms again a clear colourless “ border” to the pigmented 
disc. But immediately the outpushing of the threads recom- 
mences, and seems to proceed by a straightening and disen- 
tanglement of the individual threads, which grow in length 
as one watches them, apparently being extruded from the 
central mass. The commencement of the process of expansion 
of the threads is shown in a drawing of another specimen 
(Plate 15, fig. 4). 
In all cases the process of expansion is accompanied by the 
formation of “ vacuoles”? in the colourless border-substance 
(see figs. 1—4), which change their shape and position as 
the spreading goes on. But they have not the character of 
the ‘contractile’? vacuoles of Heliozoa, although Archer 
speaks of such “ contractile ” vacuoles (perhaps by inadvertent 
use of the term “ contractile”) as occurring in his C. labyrin- 
thuloides. Archer also observed frequently solid food par- 
ticles such as diatoms to be entanged in the substance of the 
colourless material. I never observed any food particles thus 
engulfed in C. montana. 
The threads are of extreme tenuity, of equal diameter 
throughout, and appear to me not to undergo any measurable 
change in dimension. I did not see them shorten and thicken, 
but they appeared to become flexed and gathered together 
when a stimulus was applied to them. Further, I never saw 
any thread either fuse with a neighbouring thread or divide 
into two. It appeared to me (but the observation is difficult) 
that when two threads come together they may be very closely 
apposed, but nevertheless retain their distinctness; and con- 
versely that, where a thread seems to divide into two longi- 
tudinally, the case is really one of the separation of two pre- 
existing threads. 
My general conclusion is that the threads do not really 
form either a dendritic branching figure or a network, but are 
merely apposed so as to form when less expanded, or, to speak 
more accurately, when less straightened, an apparent meshwork, 
aud when more straightened and separated from one another 
