the late Professor Ritdolphi, 2^3 



beginning of a manuscript remark written long afterwards in his 

 own copy of the work. Besides some new essays, Rudolphi also 

 includes in this publication remarks on subjects previously in- 

 vestigated by him. He first of all treats of different portions 

 of the eye, proving. that the zonula is a different structure from 

 the retina ; of the crossing of the nerves of sight in fishes ; of the 

 structure of the teeth ; of the ventricles of the brain ; of hyda- 

 tids ; of the breathing of frogs ; of the structure of the vilU 

 intestinoriim, and of Peyer's glands. In the last essay he de- 

 scribes, in reference to many different animals, the varieties of 

 external structure of the glands of Peyer, bodies which, not long 

 previously, were represented as accidental and diseased occur- 

 rences. How correct he was, has been proved by the import- 

 ance which this subject has subsequently acquired. Rudolphi, 

 in discussing these puzzling bodies, did not treat of their inter- 

 nal structure, which perhaps, at that time, he alone could have 

 explained. This investigation was not rendered so necessary 

 till the cholera and the typhus ahdominalis had surprised many 

 in their ignorance of the existence of those structures, which 

 Rudolphi had as it were introduced anew into the science. 



By his essay on the villi intesti?iorum, Rudolphi obtained a 

 still more important position among the anatomists who had 

 occupied themselves with the structure of the tissues ; and al- 

 though he denied the existence of vessels in the villi^ and re- 

 fused to admit the presence of villi in fishes, yet his observa- 

 tions have shewn the errors of the ancients in respect to the 

 visible openings of these portions : he also distinctly pointed 

 out in some cases the epithelium of the villi intestinorum, and 

 by examining the variations in the occurrence of these organs, 

 placed limits to the physiological hypotheses. Rudolphi re- 

 mained almost quite general in the views taken in this work. 

 In his own copy of the book, there is the following manuscript 

 note : " Libruvi duodecim annis elapsis legi anatomicus duo- 

 decies melior ac turn temporis eram, plurima tamen probo.'" 



In the year 1802, Rudolphi made a journey through a portion 

 of Germany, Holland, and France; and published (1804) his 

 observations in the departments of natural history, medicine, and 

 the veterinary art. This tour developed a wonderful abundance 

 of knowledge in botany, zoology, pathological anatomy, and 



