No. 473] 



NOTES ON LEPTOPHRYS 



337 



numerous specimens were found which did not show such a clear 

 margin. Many specimens were seen which were quite free from 

 food particles, but no staining of these would bring out a differen- 

 tiation between the refractive granules and what might have been 

 taken for nuclei. The figure of Hertwig and Lesser leads me to 

 suspect that what they had taken for nuclei with central "nucleoli" 

 were monads ingested as prey. It is unfortunate that they did not 

 state how they determined these bodies to be nuclei. 



Locomotion is effected by a more or less active amoeboid move- 

 ment. An active large individual tosses itself about very much as 

 a cloud of smoke is distorted by a current of air. On the other 

 hand the movement may be slow and deliberate. 



The large individual represented in Fig. 1, took in as food dia- 

 toms, desmids, and what may have been several Infusoria. On 

 IMarch 22, 1905, in a bottle, that since March 12 had contained 

 living Chlamydomonas reticulata, I found numerous specimens 

 some of which belonged to L. cinerea and others which I had to 

 place under the species L. elegans. They were feeding upon the 

 Chlamydomonads. In one case I saw an individual that had 

 ingested at least 25 Chlamydomonads. These flagellate forms 

 after being ingested were greatly reduced in size. One specimen 

 was found which had ingested a single Navicula sp. The inges- 

 tion of food was carefully observed. It was done, so far as could 

 be seen, just as an Amoeba envelops its food, but the closing of the 

 ectosarc about the prey in the fashion of an iris diaphram could 

 not be made out. The food appeared to be partially digested 

 while the animals moved about. This inference is based upon 

 the broken-down appearance of the ingesta. The food is eventu- 

 ally assembled into a common vacuole more or less centrally dis- 

 posed. 



Some time after the animal has gorged itself with food, or formed 

 a central common vacuole of food, it withdraws its pseudopodia 

 and enters into an encysted condition. Numerous cysts have 

 been seen and studied. A single individual has been obser\^ed 

 ingesting food and was followed through its complete encystment. 

 From the time when the animal had quieted down and ceased to 

 ingest food to when it left the cyst, a period of five hours had elapsed. 

 The cyst varies in size and shape, depending upon the size of the 



