1 2 BIBLIOGRAPHY. 



are undoubtedly minute sedentary Flagellata, such as Spitvtella or Oiko- 

 uionas. 



The issue of the ' Philosophical Transactions ' following upon the 

 one containing the foregoing figures and descriptions, is conspicuous for 

 the insertion, at the hands of an anonymous writer, of an account of 

 a considerable number of infusorial forms obtained from an infusion of 

 pepper. The type first described by Leeuwenhoek, Vorticella micro- 

 stovnmi or pittrinwn, is here figured for the first time, as also Paranieciinn 

 aurelia showing its charactei'istic ciliation, a species of E?iplotcs, Enchclys, 

 OxytricJia, and a variety of other animalcules whose identity cannot so 

 easily be determined. Among the delineations given of the Eiiplotes, one 

 example represents an animalcule dividing by transverse fission, and is 

 referred to in the accompanying text as a probable example of copulation. 

 The highest interest attached to this early contribution to microscopic 

 literature is, however, associated with the fact that it embodies a remarkably 

 clear and graphic account of several species of the exceedingly minute 

 and low-organized Phytozoa, Vibrio and Spirilluin — briefly referred to by 

 Leeuwenhoek in the preceding quotations as " an infinity of little particles 

 like very thin hairs which drove through the water " — which is accompanied 

 by illustrations of the types observed, equal both in execution and the 

 scale of magnification employed to those produced by workers in this same 

 field of research for more than a century later. The apparatus, nevertheless, 

 at the disposal of this early investigator was the single-lensed instrument 

 only manufactured by Mr. Wilson, but out of which he testifies to having 

 succeeded in obtaining a magnification of no less than 640 diameters. In 

 recognition of their attenuate serpentine form and movements, this dis- 

 coverer proposed to confer upon the hair-like bodies just referred to the 

 distinctive title of " Capillary Eels." A brief abstract of this anonymous 

 author's original and earliest recognizable description of these exceptionally 

 minute and highly interesting organisms is here appended. After submit- 

 ting an account of the instrument employed and various forms observed by 

 him in his infusion of pepper, he continues : — 



" One sort I never discovered till but three or four days ago. These are very 

 long slender worms, of which my pepper-water is prodigiously full. They are all of 

 the same thickness, but their lengths are very different, some twice and some thrice as 

 long as others, and at a medium I judge the proportions of their length to their breadth 

 at least as 50 to i. To the largest magnifiers they look like threads of horse hair, 

 (to a naked eye), from a quarter to three-quarters of an inch long, and their motion 

 is equable and slow and generally they wave their bodies but little in their progres- 

 sion, though sometimes they make greater undulations. But what is more remark- 

 able, they swim with the same facihty both backward and forward, so that I can- 

 not distinguish at which end the head is, and I have seen the same worm go 

 forward with one end, and back again with the other end foremost about twenty 

 times together. And sometimes they will (like leeches) fix one end on the glass 

 plate (on which I lay the water), and move the loose part of their body round 

 about very oddly. These I take leave to call Capillary Eels, and I have given you 

 as well as I could a representation of their appearance to a great magnifier, in the 

 several postures I have seen them swim. 



