MODERN BIOLOGY 353 



zoological museum, now one of the finest in the world, and did much ex- 

 tremely successful educational work; he was highly esteemed by pupils and 

 friends on account of his zeal for science and his noble, almost supersensitive 

 temperament. He could never get himself to perform vivisections and once 

 declared that even the prospect of world-wide fame would not induce him to 

 possess the insensitiveness of a Brunner.' At the same time he was severely 

 critical towards others as well as towards himself and laboured hard for 

 the abolition of the mysticism that natural philosophy had introduced into 

 biology, so that his writings, in spite of a number of inaccuracies, give on 

 the whole an impression of solid reality and of being far more modern than 

 those of many of his famous contemporaries. 



Ktidolphf s work on -parasites 

 It is in three particular branches of biology that Rudolphi has made valuable 

 contributions: parasitic research, comparative anatomy, and physiology. In 

 the first-named he is a pioneer; his work Entozporum historia naturalis has so 

 considerably widened the knowledge of intestinal worms which Pallas 

 founded that all subsequent research has been based on it; this work is the 

 result of investigations into numerous germ-carrying animals and gives de- 

 tailed accounts of the appearance and conditions of life of the parasites 

 existing in them. Through this work the number of known species of intesti- 

 nal parasites has tripled. But while Pallas believed that the parasites or their 

 eggs enter the host from outside, Rudolphi is convinced that they are pro- 

 duced by diseased processes inside the hosts — a false idea, which is all the 

 more curious because otherwise he most emphatically denies the possibility 

 of spontaneous generation. In these circumstances it is natural that his 

 account of the evolutional history of the intestinal parasites should be the 

 weakest part of his work and far inferior to the masterly description that 

 he gives of the different forms. 



In a collection of short essays Rudolphi has recorded a number of valu- 

 able investigations in comparative anatomy. Of special interest are his com- 

 parative microscopical studies of the intestinal villi in different vertebrates. 

 He gives an account in this work of a large number of different forms of these 

 appendices, thereby increasing not only the knowledge of the tissue theory 

 as created by Bichat, but also the use of the microscope. This investigation 

 therefore deserves to be remembered as one of the first in the sphere of com- 

 parative histology. Another useful work of his was the study of the cerebral 

 cavities, wherein he attacked Sommerring's above-mentioned theory of the 

 cerebral fluid's being the intellectual organ and his belief in connexion there- 

 with that the nerve-fibres end in these cavities. Rudolphi considers that the 



' JoHAN Conrad Brunner (165 3-1737), whose name is preserved in the glands of the 

 duodenum called after him, made some well-known experiments with the extirpation of the 

 pancreas of live dogs. 



