Torquatella typica; a New Type of Infusoria, Allied to the Ciliata

Field: Agricultural and Biological Sciences (Life Sciences)

ABSTRACT Two years ago, at Naples, I found and made sketches of a very curious little Infusorium, which is sufficiently remarkable to deserve record, though I have but few details of its structure to communicate, and only met with it in one “gathering.” It occurred in connection with a mass of eggs of Terebella which I was keeping for the study of the development of that annelid. Other Infusoria—true ciliate heterotrichous forms—were abundant in the same vessel of sea water, feeding on such of the eggs as were in a decaying state. Some of these contained red masses which they had engulphed— detached fragments of the broken-down TereBeila eggs. Others were busy in making their way through slits in the chorion of certain eggs, eager to enjoy the feast within, and some of the egg-shells contained two or three Infusoria hopelessly drifting round and round, having eaten all the semi-decayed egg-yelk and apparently unable to return by the slit which had admitted them—most unquestionable cases for the foundation of elaborate theories of “heterogen etic metamorphosis ” on the part of rashly speculative nature-philosophers — but such as are well enough known to assiduous students of the minuter forms of life. Here and there, among these swarming ciliate Infusoria, I observed the specimens drawn in Pl. XII, figs. 1—5. They were exceedingly active, and had to be examined both in the living condition and after their movements had been arrested by the administration of a trace of Osmic Acid, in order to ascertain definitely their characteristics. Though having the appearance and habit of a ciliate Infusorian, this form—for which I propose the name Torquatella—does not possess any cilia at all. The body is oblong;, and has the same mobility as that exhibited by most of the Ciliata. At the anterior extremity is placed the mouth, overhung by a capitular prominence, or upper lip (c c), as is not unfrequent in the group. There is a definite cuticular membrane to the body-sac, but, contrary to what occurs in most ciliate Infusoria, this does not transmit any delicate processes of vibratile protoplasm. There is not even a ring of such cilia surrounding the oral region and capitular prominence, as in Vorticellidœ, but in its place a complete delicate bell-like prolongation of the body wall, which may well be compared to an Elizabethan frill or plicated collar. This large collar quite overhangs the cephalic region, and reaches in front of it. It is no mere cuticular expansion, but has protoplasmic characteristics, being continually in a state of vibration, alternately closing up and expanding with a twisting movement, and exhibiting the same rapidity and regularity in this movement as do a series of cilia in a similar position. In fact, the movements of this collar may be best understood by comparing them to the movement of a series of cilia united to one another along their length by delicate membrane. In figs. 1—3 the collar is seen in a quiescent condition, when it exhibits obliquelydirected folds. In figs. 4 and 5 it is seen at the other extremity of the stroke, that is to say, expanded.