No. 416.] PROTOZOA OF ESPECIAL INTEREST. 655 
food, and observed that the ends of the tentacles were attached 
to threads of algae which appeared to be ruptured at the points 
touched, and he concluded that a secretion of some sort is poured 
out upon the alga by the tentacle. He also maintained that the 
organism is exclusively a plant-eater. Von Erlanger described 
the tentacles as possessing a stiff dart or needle-like trichocyst at 
the end ; these, he said, are drawn in with the tentacle until, 
when the tentacles are entirely withdrawn, they form a peripheral 
layer of trichocysts as in a Prorodon. He also observed that the 
organism may swallow other living forms and described the 
seizure of a small flagellate by the cilia about the mouth opening. 
There are a few points which I may be able to make in 
addition to the above. The organism, when feeding, lies 
attached to the bottom of the vessel by its oral tentacles 
(.e., those about the mouth, which are no different from the 
others on the animal) and mouth downwards. This brings 
the posterior end of the organism upward, and the anal spot 
and contractile vacuole can be easily seen and studied while 
the animal is in this position. The vacuole is not in the center 
of the dorsal surface, but lies a little to one side (Fig. 4). The 
tentacles are almost as distensible as the neck of Lacrymaria, 
and may stretch out a distance of two and a half diameters 
of the organism, or retract until they disappear in the body. 
They arise from the substance of the cortical plasm, which is 
covered by a very thin cuticle or outer membrane, but they 
cannot be traced into the inner plasm. The cilia are more 
like flagella than cilia, and move with a vibratory rather than a 
stroking motion ; while resting they are easy to follow, but 
when the tentacles are all withdrawn the motion becomes 
much more rapid, and only the general waving surface can be 
made out. 
It is when the animal is quiet that it takes in food. It 
remains for hours, sometimes, without giving a sign of feed- 
ing, but the tentacles are stretched out to their greatest 
length and it appears to be merely waiting for something to 
come. Things do come, especially flagellates like Chilomonas, 
Trachelomonas, Euglena, etc., and ciliates such as Urocen- 
trum, Parameecium, Bursaria, Colpoda, etc., but no attention is 
