M. Ehrenberg's Researches on the Infusoria. 



viously marked four of these vibratory points, situated regularly 

 opposite to each other. This led him to infer that this little 

 animal, and the Brachionus urceolaris, in which, for the first time, 

 he had observed these vibratory motions, would manifest these 

 organs the most distinctly ; and this he found to be the case. 

 They are less distinct in the Hydatina senta, the Cycloglena 

 lupus, and a new and very large species resembhng the Notorri' 

 mata centrura, which is distinguished by lateral cirri, not unlike 

 wings ; and which he has named Notommata copeus. Since the 

 Brachionus urceolaris belongs to the cuirass-rotatory animals, 

 and since the organs in question are also found in the Euchlanis 

 macruray their existence is demonstrated in the two orders of the 

 class of Rotatoria, and in the three families of the Hydatina, 

 the Euchlanidia, and the Branchionia. 



The number of genera in which these organs have been 

 hitherto discovered is six, and the number of species is eight. 

 At the same time, M. Ehrenberg believes that these are not the 

 only species which possess these organs, and the more so as they 

 are often very difficult of discovery. It is thus he remarks that 

 he did not succeed in discovering them in the Hydatina senta 

 which he had examined more than a hundred times, and with 

 the greatest possible attention, after the greatest possible care, 

 and having published the details of its organization in plates, 

 which were engraved in the SymholcB PhysiccB. All these re- 

 searches previously made had not supplied him with the slightest 

 suspicion of their existence ; whereas now he can easily demon- 

 strate them to any one who would wish to see them. Very pro- 

 bably their discovery presents similar difficulties in all the rota- 

 toria, and these must be overcome before we can hope to see the 

 organs. 



More lately M. Ehrenberg found an opportunity of exa- 

 mining the Notommata clavulata. (See PI. I. figs. 8 and 9.) 

 Considering the size, and the great transparency of this animal, 

 he always thought that the organs in question should exist in it. 

 After some labour he found them, and in extremely interesting 

 relations. They are not adhering to the seminal organs as in the 

 other infusores, but they are attached to a distinct vessel, which 

 is free, very thick, and very transparent. He counted more than 

 thirty small clubs attached to this vessel, in a simple line, and 



