128 PATHOLOGY 



the doctrine of spontaneous generation, which ruled for thousands 

 of years, had not vanished from science, and in the beginning of 

 the last century natural philosophy treated with preference on the 

 beginning of life, and some are not lacking in our day who believe 

 that they see in the doctrine, that the tissues of our bodies break 

 up in decomposing into small organisms, 1 an expression of the 

 immortality of the life principle. 



That the large intestinal worms do not arise from the dirt of the 

 intestinal canal, from saburra, but that for them Harvey's rule 

 holds, has been shown by both zoologists and pathologists. For 

 the smallest beings we may mention the chemist, L. Pasteur, with 

 the physician, Robert Koch, the former of whom conclusively dis- 

 proved the spontaneous generation of microorganisms; the latter 

 as the discoverer of the methods which permitted us to ascertain 

 simply and surely the constancy of form of a microorganism and 

 to give incontrovertible proof that in every single microorganism 

 the law of generation was true, not entirely in Harvey's sense, but 

 in the more general form: Omne vivum e vivo ejusdem generis. 



But it is not only general biology which has been furthered by 

 the parasitology of the physician, but also special biology and the 

 systematic classification of parasitic animals and plants. Just here 

 is plainly shown that pathology cannot in any way be separated 

 from the other natural sciences, as it is not only the receiver which 

 makes practical use of scientific discoveries, but also the producer 

 which by its own effort, and through independent performances 

 furthers science. The modern development of bacteriology, the 

 determination and elaboration of exact methods of investigation, the 

 morphology and biology of bacteria, have not been entirely developed 

 by botanists, but it has been and still is physicians and pathologists 

 who may claim a large part of the results as due to their efforts. 



The same relation in working together exists between pathology 

 and zoology in regard to the parasitic animals. Here the points of 

 contact of the two sciences are doubled, for on one hand the change 

 of generations of many human parasites, their occurrence in different 

 hosts, as well as the fact that animals may be the simple conveyers 

 of parasites, required the human parasitologist to bring the animal 

 world into the realm of their investigations; on the other hand, the 

 morphology and systematic study of the parasitic animals themselves 

 has been ascertained with considerable assistance from pathologists. 

 In the first class I will only recall the joint work of pathologists 

 and zoologists on trichinosis. 2 In determining the relation of this 



1 R. Arndt, Unters. uber d. Enischung von Kokken und Bakterien in organischen 

 Substanzen, Virchow, Arch., 82, p. 119, 1880; A. P. Tokker, Versuch. einer nauen 

 Bakterienlehre, 1903. 



2 Zenker, Arch, i, p. 90; Leukart, Unters. tib. Trich. spiral. 1866, R. Virchow, 

 Lehre von den Trichinen. 



