224 



THE AMERICi^N MONTHLY 



[Decemb 



mbe!? 



is the case with Vorticella, etc. Ne- 

 vertheless, some part of the current 

 produced by the vortex must pass into 

 the shell, -or at least into the neck, 

 and invisible particles in the water 

 are appropriated by the creature for 

 its nourishment. 



When the shell was disposed verti- 

 cally to the observer, the wide, belt- 

 shaped mouth and upper part of the 

 neck are clearly seen, and no cilia 

 nor even sarcode could be made out 

 in those parts ; the body of the shell 

 contained a yellowish mass, of clear, 

 jelly-like appearance, transparent, but 

 so deep that its yellow color rendered 

 the outlines of the sand-grains com- 

 posing the fundus of the shell indis- 

 tinct, although they were visible 

 through it. No movement of this 

 jelly-like mass could be seen, even 

 with a Hartnack \ objective and high 

 oculars, although the vortex in the 

 water was observed at the same time. 



When the jerking movement com- 

 menced the vortex stopped, and as 

 the shell ceased its violent swaying 

 and began to sink by its own weight 

 to a vertical position, the vortex re- 

 commenced. The periods of quiet 

 were from three to ten times the dur- 

 ation of the periods of jerking up and 

 down. 



Later on I obtained a gathering 

 from the water-supply in which I ob- 

 served this same form 

 swimming freely. It 

 moved in a slightly 

 oblique position with 

 the mouth uppermost 

 and advanced, rotating 

 slowly at times, and 

 again sailing smoothly 

 along without turning 

 on its axis. It fre- 

 quently bumped rough- 

 ly against diatoms and 

 other masses of en- 

 tangled matter in the 

 water, in which case it 

 usually paused but for 

 an instant and sailed 

 away again, but occa- 

 sionally it remained in contact with 



such masses of matter for some mo- 

 ments, during which time the charac- 

 teristic vortex was seen in full play. 

 This specimen was not seen to go 

 through the performance of attach- 

 ing itself and jerking about, but when 

 starting from a state of rest into mo- 

 tion it started with a movement very 

 much like a jump, often turning a 

 quarter round with the first impetus 

 and swimming quickly off. No cilia 

 could be discovered in this speci- 

 men with any objective up to a one- 

 eighth. 



There is no work accessible to me 

 by which I can determine the genus 

 and species of this organism, and I 

 submit my observations in the hope 

 that someone who has the means 

 may determine it, and inform us 

 through the columns of the Jour- 

 nal. It is a high tribute to the 

 genius of Prof. Leidy that he was not 

 misled, even when examining dead 

 shells, by the remarkably exact re- 

 semblance of this form to undoubted 

 Rhizopods, into pronouncing it to be 

 certainly one of that class. 



Useful Apparatus. 



Whoever has found occasion to 

 mount objects, such as foraminifera, 

 which must be selected from a mass 

 of sand and other debris, cannot fail 



Fig. 49. 

 to appreciate the usefulness of such 



