OBSKKVATIONS ON LIVING SPECIMENS. 7 



OBSERVATIONS ON LIVING SPECIMENS. 

 MOVEMENT. 



Specimens belonging to several families were kept under observa- 

 tion at difTerent times. It was found in all cases, where no injury 

 to the animal had taken place, that pseudopodia were thrust out 

 within 5 minutes of the time of contraction. This was true of 

 Iridia and HaUphyscma in the Astrorhizida), Discorbis in the 

 Rotaliidie, Polystomella in the Nummulitidae, and Quinqueloculina, 

 Orhiculina, and Orhiioliies in the IMiliolidae. 



One observation of much significance, in view of the widespread 

 view that individuals of various species or even genera may unite, 

 seems to entirely disprove this theory. In all cases where specimens 

 of the same species even were brought near enough to have their 

 pseudopodia touch there was a repellant rather than an attractive 

 action. The same was true of specimens of different species and 

 those of different genera. While specimens were under observation, 

 they occasionally altered their course abruptly. In such cases it 

 was often found that the pseudopodia of the specimen under observa- 

 tion had come into contact with those of another. In all such cases 

 the first specimen changed its direction, usually rotated the test 

 somewhat, and started off in a new course, often 90° from that in 

 which it was at first traveling. 



Portions of the same specimen, however, when separated by 

 cutting, threw out pseudopodia rapidly, and when those of one 

 part touched those of the other they quickly anastomosed and the 

 two ma.sses moved toward one another and coalesced. 



The rate of movement of the protoplasm in the pseudopodia was 

 recorded in Iridia diaphana and Orhitolites duplex. The unit of 

 measurement in all experiments was 10 units of the micrometer 

 scale, which on the slide represented about 0.2 mm. As in the 

 movement of the whole test, there is apparently a rhythmic move- 

 ment instead of a constant one. In one specimen of Iridia diaphana 

 the movement along the more slender pseudopodia was as follows 

 for the return current — the rate in seconds for the 0.2 mm. 



8, 8, 8, 9.6, 7.5, 10.2, 8 seconds. 



The average of movement in the slender pseudopodia was about 40 

 seconds per millimeter. In large coalesced pseudopodia it was 

 slower, averaging about 60 seconds per millimeter. 



One group of records shows the rhythmic character in 10 suc- 

 cessive units of 0.2 mm. each: 



10, 8, 7.8, 8.4, 9.2, 10, 9.4, 9, 8.2 seconds. 



A series of measurements of the pseudopodia in Orhitolites duplex 

 gave the following for 0.2 mm. units: 



12.8, 8.8, 9.2, 14, 12, 7.8 scfond^. 



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