134 Notes on some apparently undescribed [February, 



The creature, when in a healthy or comfortable condition, is 

 very slightly if at all changeable in shape. When about to die it 

 takes a sub-spheroidal form and becomes diffluent, but this stage 

 is at times postponed until the animal has passed a short period 

 as a granular amceba, with a large and conspicuous contractile 

 vesicle, slowly moving by a forward flow of a sarcode wave unac- 

 companied by the posteriorly located granules. The motion of 

 the Heteromita when swimming is rapid and oscillating, being a 

 forward movement by short zig-zags, the animal at the same time 

 rotating on its longitudinal axis. 



The anterior vibratile flagellum is ordinarily extremely difficult 

 to detect. The zooid, when attached, rests at the extremity of its 

 anchoring flagellum, and when viewed dorsally the vibrating lash 

 is visible for only the very short distance between its origin and 

 the point where it curves to pass beneath the lower or ventral 

 surface (as in Fig. i), this part being flexible but apparently not 

 vibratile. Even when in a favorable position for its own demon- 

 stration, the rapidly-moving filament becomes visible only after 

 careful manipulation of the mirror, or after the infusorium has 

 been killed by iodine or osmic acid. Small particles are not 

 affected by its motion until they have floated past the anterior 

 margin of the body, sometimes almost in contact with the surface, 

 when they fall into the stream and are dashed upward, at times 

 performing a complete circuit around the animal to the starting 

 point. If solid food is taken, which I doubt, it must enter through 

 the ventral surface. No solid particle has been seen to pass into 

 the endoplasm, although I have tried to feed the creatures with 

 indigo, and have had the same individuals in a growing-slide for 

 four full days surrounded by myriads of bacteria. 



The contractile vesicle pulsates quickly and sharply once every 

 nine seconds. The only method of reproduction observed is by 

 longitudinal fission. The species here referred to is remarkable 

 for its stability of form and for the position of its tractellum or 

 vibrating flagellum, the latter peculiarity having been recorded for 

 no other member of the genus. 



In the same animal maceration, as the Heteromita- weie disap- 

 pearing, many ciliated infusoria were developed, which, according 

 to the latest .schemes of classification, can be relegated to the 

 genus Tillina only, although, so far as external cont( ur is con- 

 cerned, the resemblance is remote. This difference of forpi, h<nv- 



103 Y( 



