A NEW FIELD FOR THE MICROSCOPIST. 
117 
or pseudopodia of an amoeba or other Rhizopod. As in the 
pseudopodia of certain Rhizopods, such as the Foraminifera, it 
will likewise be found that notwithstanding the extreme tenuity 
of this sarcode film, a circulation of its substance is being con- 
stantly maintained, flowing upwards on the outside, over the 
distal edge or rim, and downwards on the inner surface, at the 
base of which it again comes in contact and merges with the 
general sarcode of the body. The services performed by this 
wineglass-like film of sarcode as a branchial or respiratory 
organ are doubtless considerable, but this by no means repre- 
sents its most important function. In conjunction with the 
centrally enclosed vibratile flagellum it represents the most 
admirable trap or snare for the capture and retention of food 
that can be possibly imagined. Whirling round with incon- 
ceivable rapidity this last-named organ, the flagellum, creates a 
strong current in the water, setting from behind forwards in the 
direction of its own apex, and bringing with it all such tiny 
organic particles as do not possess sufficient power to stem its tide. 
But for the outspread collar these atomic particles would simply 
hurry with the stream past the monad’s body and out of reach. 
Not for them, however, such an easy passing of the rapids. 
The dangers of dread Scylla lurk midway in the whirlpool of 
Chary bdis! In the midst of their swift career they strike against 
the outer surface of the almost impalpable film of sarcode of 
which the collar is composed, and to this they now adhere as 
tenaciously as the snared bird to the lime-covered twig, or an 
incautious fly to a spider’s web. Then slowly, almost imper- 
ceptibly, the captive atoms, be they alive or dead, are carried 
along with the circulating current of the collar’s substance, 
until, on reaching the base of the interior of this structure as 
just now described, they are there engulphed within the sarcode 
substance of the monad’s body as within a living grave. A 
diagrammatic illustration of the modus operandi of this remark- 
able feeding process, and also the aspect presented by one of 
these monads that was induced to make a hearty meal off minute 
particles of carmine, will be found at PI. III. fig. 1 9. The food- 
particles after ingestion, as above, are gradually accumulated into 
spherical agglomerations and then passed within the interior 
of the body in a manner identical with that accompanying the 
feeding process of Vorticella or other of the higher Infusorial types. 
Refuse, or undigested residual particles of food, are finally libe- 
rated from the same area, limited by the base of the collar within 
which they primarily gained access. In common with apparently 
all other representatives of the Protozoa, these minute collar- 
bearing monads possess from one to two or more of those rhythmi- 
cally expanding and contracting spaces distinguished by the title 
of “ contractile vesicles.” With these structures there is usually 
