AND PHYSIOLOGY OF TRICHODINA. 115 



series of deductions and generalizations -whose influence shall be felt beyond the brief, 

 flitting period in which they were produced. 



That investigation which, although confined within a narrow circle, is the most thorough, 

 and at the same time truthfully recorded, is far more valuable for the future than a course 

 of observations which extends over a larger field, and is carried out on a grander scale, but 

 lacks the element of completeness. A thorough and elaborate study of one single species 

 will carry the possessor of such knowledge immeasurably deeper into the secrets of life, and 

 inconceivably further along the road of progress, than a superficial, lightly tripping survey 

 of the whole kingdom of animals. In the former case, for each newly discovered fact the 

 naturalist takes one step higher on the hill of science, whilst in the latter he is forever 

 trying to get the first foothold in the ascent. 



Of all the Protozoa there are none which have so great a claim upon the naturalist's 

 time for investigation as the Vorticellidae. The want of a precise understanding of their 

 structure led, in the first place, to their being classed with the Zoophyta, and — simply on 

 account of their similarity in form — among the Hydras. This was the first retrocession. 

 After Ehrenberg had promulgated the opinion that they possessed a distinct intestine, whose 

 two ends approximated each other, we find Van Der Hoeven, in the second edition of his 

 * Handbook of Zoology," comparing them to the Biyozoa, and avowing his belief that their 

 future place will be among the lowest groups of Mollusca. Here we have a still deeper 

 plunge into the vortex of confusion ; not so much however, if at all, to the discredit of 

 the Hollandish naturalist, as to that of those who came after him. The apparent simi- 

 larity of the organization of the Vorticellidae to that of the Bryozoa was no small warrant 

 for his suggestion ; but, after almost every microscopist of any degree of reliability, who 

 looked at these infusorians, had disproved and denied the presence of the intestine, so 

 elaborately set forth by the Berlin micrographer, and nothing was left but a mere resem- 

 blance in outward form to the Bryozoa, that was, to say the least, a very far-fetched 

 comparison when Professor Agassiz homologized them with the Mollusca, declaring that he 

 had satisfied himself of the " propriety of uniting the Vorticellida; with Bryozoa." 



Ere this, too, Lachman (Mull. Archiv. 1856) had shown that the whole group of ciliated 

 Infusoria possessed a conformity of organization altogether unlike that of any other. The 

 profound researches of this early lamented observer left no doubt as to the dissimilarity 

 between the Vorticellidae and Bryozoa. Here was, at last, a step taken in the right direc- 

 tion ; and when this author, in connection with Claparede, published the " Etudes sur les 

 Infusoires et les Rhizopodes," the climax of proof was attained in the abundance of details 

 presented in that remarkable volume. Among the many questions which are discussed in 

 that work, that of the unicellularity of the Infusoria receives a considerable share of atten- 

 tion ; and a decided ground is taken in favor of their pluricellularUy ; not so much, how- 

 ever, on account of their being known to consist of more than one cell, as of the fact of 

 their possessing such a variety of organs and performing so many diverse functions. 



The greatest variety of this kind is most elaborately exemplified by the group of Vorti- 

 cellidae ; but yet it rises, from the lowest of the class, through such insensible grades that 

 the relations of the type of the two extremes are never lost sight of amid the growing 

 complicity of the organization. 



Among the many forms which more than usually excite the interest of the observer, 

 there is no one in the whole class of Protozoa that surpasses the allurements of the remark- 

 able creature which forms the subject of the present memoir. This is accounted for by a 



