THE POLYGASTRICA. 5 



tion than is the case with those of Ehrenberg in this his chosen 

 field of research. 



The Rotifera are now, by common consent, ranked with the 

 lower divisions of the Articulate animals, with which, as Ehren- 

 berg himself had pointed out, their complicated structure evi- 

 dently brings them into close relation ; so that thus, at a stroke, 

 .one of the two great primary groups of the Infusoria has been 

 taken away. Then, with respect to the Polygastrica, although 

 their rejection as a division of the Infusorial Animalcules has 

 been neither so summary nor so complete as that of the Rotifera, 

 their treatment by the most competent observers of the day is, 

 in every respect, far more damaging to the authority and in- 

 fluence of the great microscopist of Berlin. 



In the first place, it is now generally allowed that the term 

 Polygastrica is altogether inapplicable, inasmuch as no such 

 multiplicity of stomachs as was alleged is found to exist in any 

 of the organisms to which it was applied. Ehrenberg was led 

 to the opinion he entertained on this point by a somewhat 

 curious expedient, first adopted, we believe, by Baron Gleichen, 

 and which certainly exhibits his ingenuity and fertility of re- 

 source in a very favourable light. A very general characteristic of 

 these so-called Polygastrica is, that they exhibit, in the interior 

 of their substance, a number of clear spaces, resembling so many 

 minute sacs in some of the species these vacuoles, as they are 

 termed, numbering upwards of a hundred. It occurred to 

 Ehrenberg that possibly these vacuoks were stomachs ; and, in 

 order to test the accuracy of his conjecture, he tried the experi- 

 ment of feeding the animalcules, employing for the purpose 

 coloured substances, such as carmine and indigo, the particles 

 of which, if imbibed, would, he knew, be readily discernible 

 through the gelatinous substance of the animals' bodies. The 

 experiment was perfectly successful. The delighted philoso- 

 pher saw numbers of the minute beings coursing over the field 

 of his microscope, with little specks of colouring matter dis- 

 tinctly visible within them. P^hrenberg had now no longer a 

 doubt that the internal clear spaces were really stomachs ; and, 

 rendered enthusiastic by his singular discovery, he subsequently 

 saw, or rather fancied he saw, distinct traces of a connecting 

 intestinal canal. 



No wonder, therefore, that from characters so marked and 



