146 THE AMERICAN MONTHLY [July, 



from about y^j-fl-th to ^J^o-th of an inch in length. The form of the 

 body in some of these infusiorians as observed by me was ovate, in others 

 pear shaped, or pyriform ; both forms are delineated in the plate. 

 The color was whitish, the tentacles and pedicel being hyaline. At 

 the point of junction with the body the pedicel in some cases expanded 

 abruptly, but not in the manner shown in Kent's illustration of P. 

 Steinii. In one case only the tentacles presented a knobbed appearance, 

 and in this instance one of them was curved over, as shown in frontis- 

 piece fig. i. Ehrenberg says it is interesting to see this animalcule 

 seize its prey with its tentacula. I noticed several spirillce (with 

 which the water abounded) and other minute pai*ticles adhere for a 

 short time to a tentacle ; but as they always freed themselves without 

 any apparent injury I did not regard this as the function observed by 

 Ehrenberg, although the curved tentacle was eminently suggestive of 

 the curving tentacles of Drosera ; and, therefore, of the act of prehen- 

 sion. The bodies of these infusorians are filled with granular protoplasm , 

 similar to that observable in many other animalculae, and each contains 

 near its upper and free end an active contractile vesicle. In one the 

 granular matter was centrally massed, as shown in one of my sketches. 

 There are two or three points of general interest to which I may, 

 perhaps, usefully refer in closing. The tentacles of Podophrya differ 

 from those of the various species of Hydra, one of which Mr. Miles 

 has given us an opportunity of observing to-night. In Hydra the 

 tentacles are studded with minute capsules which contain a filament at 

 the base of which there are four minute spines or barbs, employed by 

 the animal to wound its prey. There are also indications of formic 

 acid in the capsules. In the Acinetce the tentacles bear no such cap- 

 sules as occur in Hydra, but they possess a remarkable suctorial char- 

 acter, which, however, has not been proved to exist in all the species. 

 "When an infusorium touches the button-like end of the tentacle, it 

 usually remains adherent to it ; the end becoming still more dilated, so 

 as to constitute a sucking disk, and the ray becomes thicker and shorter, 

 the other rays at the same time making grasping movements and en- 

 deavoring to attach their extremities to the captured prey. A current 

 of chyme-particles is then seen running from the captured Infusorium 

 into the body of the Acineta. The chyme-particles form at first a 

 slender row, but afterwards collect in a drop. The body of the Acineta 

 then becomes opaque from the collection of the drops." (Mic. Diet., 

 p. ii.) Next, as to the contractile vesicle, I would refer those who 

 may wish to study this important subject to Pritchard's Infusoria, p. 

 312, 4th edition ; the Micrographic Dictionary, p. 418, and, necessarily, 

 to Kent's Infusoria, p. 69. Lastly, as to the place to be assigned to 

 Podophrya in classificatory systems, chapter vi, of Kent's work, and 

 his remarks in chapter ix (on the Class Tentaculifera : Huxley), will 

 be found useful ; though I would also suggest a reference to the articles 

 in the Micrographic Dictionary on Rhizopoda, Radiolaria, Acinetina, 

 Actinophryina, and Podophrya. 



Dr. Lustig, an Italian physiologist, has found in the liver of mus- 

 sels two kinds of micro-organisms — one harmless, the other very deadly. 

 In the stomach of small animals the latter caused death in 24 hours. 



