174 M. F. Diijardin on the Digestwe Organs of Infusoria. 



wooden figures which cliildren put in motion upon the play- 

 thing consisting of an extensible arm^ formed of splines 

 crossed lozenge-wise. This inner displacement^ which I 

 thought in 1835 capable of explanation by the change of po- 

 sition in the Infusoria, by their rotation around the axis of 

 their body, I have for two years considered as quite real, and 

 it has been well seen and described by Prof. Rymer Jones*. 

 This observer, in declaring publicly at Newcastle that he never 

 had been able to perceive the least trace of the central canal 

 described by M. Ehrenberg, nor the branches which proceed 

 therefrom to communicate with the sacculi, added that he was 

 convinced from numerous observations, that in Paramcecium 

 Aurelia and in allied species the minute gastric sacs (vesicles) 

 move in a fixed direction all round the body of the animalcule ; 

 — a fact, which of itself, says the English observer, appears to 

 be incompatible with the arrangement indicated by the Pro- 

 fessor of Berlin. To this M. Ehrenberg, without recurring to 

 the comparison to the child^s toy, answered, that it is ex- 

 cessively difficult to see the central canal (the intestine), and 

 that it was only in following the course of great masses of nu- 

 triment that he himself had been able to trace it. 



This is not what was first stated, and still less what had 

 been represented in the figures of 1830 reproduced in 1838. 

 But it is at present seen, from the very confession of the in- 

 ventor, that the whole theory of the inner structure of the In- 

 fusoria rests on ideal figures and on observations impossible 

 to be verified on those very Infusoria on which they had been 

 founded f. And be it well remembered, these observations, — 

 this discovery of the intestine, — were made previous to 1838, 

 with instruments evidently less perfect than those since em- 

 ployed by the author, and which have allowed him to discover 

 the armature of the mouth of Nassula and of Chilodon, and re- 



* In the Athenaeum, No. 567, p. 635. 



[The report in the Athenaeum contained several erroneous statements, 

 some of which were corrected in a reply to Prof. Jones from Dr. Ehrenberg 

 inserted in vol. ii. p. 121. of this Journal. — Edit.] 



f We certainly must say that we cannot see all this, and think it very pos- 

 sible that M. Dujardin will have at some future day to do, what he has so 

 frequently done already, — namely to announce that many of his present as- 

 sertions are irop hazardees. — Edit. 



