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PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 57. 



plasm out of the test. Such specimens recovered rapidly and sent 

 out pseudopodia like normal specimens in their test. The rate of move- 

 ment in these specimens was recorded in several cases. There seems 

 to be a rhythmic motion when the specimen is moving in a definite 

 direction. After an interval of rapid motion the whole gradually 

 slows up and then again becomes rapid, although the alternation is 

 somewhat irregular. The following measurements of the time of 

 traveling one-sixth of a millimeter are for consecutive intervals dur- 

 ing the time that the movement covered 4 millimeters. It represents 

 the acceleration of speed during a portion of one of these rhythmic 

 intervals : 



When two or more specimens are taken from the test and placed 

 near each other pseudopodia are sent out in the usual manner but 

 instead of fusing, as in the case of the parts of a severed specimen, 

 seem to repel one another. The pseudopodia come nearly or quite 

 in contact, then bunch up, forming a considerable mass of greater 

 density, after which the flow is in opposite directions and the proto- 

 plasm is withdrawn back to the central masses and movement 

 starts of! in other directions. A similar repelling tendency was 

 noted when two species of different families were in motion. In 

 such cases when the pseudopodia came into contact they concen- 

 trated in a similar way and the specimens then moved away at a 

 right angle or more from the original line of movement, so as to 

 avoid one another. In all the specimens examined there was no 

 case in which pseudopodia became fused except in the severed parts 

 of the same specimen. Such observations are similar to those 

 observed in Amoebae according to information given me by Pro- 

 fessor Schaefer in his work during the same time at the Tortugas. 

 Such observations do not substantiate theories of fusion of various 

 specimens of the same or different species. 



Heron-Allen and Earland in their original notes on this species 

 note that the larger specimens as a rule have coarser material in 

 the test and explain the growth of the test as follows: * 



> Trans. Zool. Soc, London, vol. 20, 1914, pp. 371, 372. 



