Branchial Organs of the Infusoria. 57 



the infiisores, in 1830, in which he employed the following 

 terms : — " I have often observed small local vibratory movements 

 performed in different parts of the bodies of Rotatoria, which I 

 regard as muscular movements ; I have also observed from time 

 to time a fluctuation amongst the organs in the abdominal 

 cavity/' It was these observations which led him to the subse- 

 quent discovery of the system of an organ which appears to ex- 

 ist in all the rotatory animals. 



A new species of the genus Notommata^ of a large size, furnish- 

 ed him, in the spring of 1832, with an opportunity of completely 

 convincing himself that these local movements in the interior of the 

 body are not merely muscular vibrations, but that they are per- 

 formed by particular organs, which are symmetrical, and which 

 occupy a fixed point. In examining the Notommata centrura 

 from behind, he distinctly remarked seven of these vibratory 

 points in the right side, and six in the left. (See PI. I. fig. 10, 

 h. b.) They were never at rest, and their position was symmetric, 

 opposite to each other, at determinate distances. Accurate ob- 

 servations have demonstrated that these points are small pecu. 

 liar organs, provided with a tail, the form of which is similar to 

 that of a note of music, which are put into vibration by three 

 small vesicles or folds bulging out at their extremity. In conse- 

 quence of the motions of the animal, it was also observed that 

 these organs floated freely in the abdominal cavity by their bent 

 extremity, whilst they were attached by their tail to two organs in 

 form of a bent club, which M. Ehrenberg, from his researches 

 upon the Hydatina senta^ regards as seminal organs. He also 

 concluded that these last organs possessed a vascular system ; 

 for, at the time of the local dilatations of the body of the animal, 

 a certain number of filaments, which may be vessels, and which 

 are free and loose, may be very distinctly observed. 



The idea which occurred to our author, when he for the 

 first time observed these small vibratory organs, was, that he 

 perceived a vascular system executing the movements of pulsa- 

 tion ; but soon he reflected there was much difficulty in admit- 

 ting so great a number of hearts in an animal which exhibited 

 no traces of a circulation ; for a time, then, he remained in 

 suspense, and proceeded to the examination of other rotatory 

 animals. In a figure of the Notommata coUaris, he had pre- 



