434 Some New Infusoria. [May, 
water at this writing is as clear and limpid and sweet as that of a 
mountain spring, and not one of those gigantic Hypotricha is 
left. Yet the bowl is still a crowded infusorial menagerie. And 
not the least interesting fact is that most of those that have died 
as well as the living are new to science. 
The lowest of those to which I desire now to refer, and per- 
haps the least abundant in its habitat, is a new member of the 
genus Atractonema, the threaded spindle, of Stein. Hitherto 
but one species has been observed, and that only by its discoverer. 
With it the body is much more fusiform than with this American 
animalcule, but the latter possesses all the generic characters of 
its foreign relative, and others which mark it as specifically dis- 
tinct. The mouth in-both is conspicuous, being especially so in 
this new form. The pharyngeal passage it is scarcely possible to 
overlook since it seems to communicate directly with the contrac- 
tile vesicle. Whether the food passes into the pulsating vacuole, 
or through it, or to one side, are questions of interest that, so far 
as I am concerned, remain unanswered, as the creature has refused 
to take food when on the microscope stage. The single flagellum 
arises within the pharyngeal passage, a point on the wall, presu- 
mably the roof, serving as the basis of attachment. This struc- 
tural feature is not mentioned, and probably does not exist in 
Atractonema teres Stein. The motion of the flagellum is very 
rapid, consisting of oscillations which give it the appearance of a 
figure of eight. That it is held stiffly coiled in that position and 
then vibrated, as is represented in the sketch (Fig. 1), I have been 
unable to determine. It has been engraved in that 
position because I desired to show the animalcule in 
its characteristic swimming attitude. When the Atrac- 
tonema has been poisoned, preferably by iodine, pref- 
erably, of course, so far as the observer is concern 
the flagellum is uncoiled and straightened. The fig- 
ure of eight aspect may therefore be illusory. 
The animalcule’s movements are by rapid writhing 
and twisting, at the same time rotating on its long 
axis. It is not changeable in shape, preserving its 
elongate, subcylindrical, somewhat vermicular form, 
Fic. 1,.°*cePt when in the agony of a toxicological death. It 
Atractonema then coils and contorts itself like a wounded snake, 
| — Bie olla flattening and expanding the body to a 
film. The character of the numerous dark-bordered 
