Text book of comparative general pathology for practitioners and students of veterinary medicine / by Th. Kitt; authorized translation by William W. Cadbury ; edited with notes and additional illustrations by Allen J. Smith.
- Kitt, Th. (Theodor), 1858-1941.
- Date:
- 1906
Licence: In copyright
Credit: Text book of comparative general pathology for practitioners and students of veterinary medicine / by Th. Kitt; authorized translation by William W. Cadbury ; edited with notes and additional illustrations by Allen J. Smith. Source: Wellcome Collection.
38/504 (page 18)
![snes of the immune animal have no afßnity, or bat little afhnity (Chemical affinity), tozvard the toxines of the infcction. The poisonous elements simply do not enter into combination with them. For example, the nervous System of the turtle is absolutely immune to the toxines of diphtheria and tetanus, and these sub- stances mav be injected into the animal entirelv without effect. Yet the toxines thus introduced may remain in the bodies of the experiment animals for months without heilig rendered inert by the juices; and should the blood of such a turtle be injected into some susceptible animal it will act in the same manner upon the latter as would the toxine itself. h rom a second point of view it is to be recognized that im- munity may depend upon the fact that some of the cclls of the animal in question are able to take up and digest micro-organisms, and thus render them harmless (Phagocytosis). This power of seizing and ingesting small particles, organic and inorganic, or dead and living cells, is peculiar especially to the motile tvpes of leucocytes (wandering cells, white blood cells), but is also possessed by giant cells, splenic and medullarv cells. and even fixed connective tissue cells (as endothelium) ; and plays an important part in the economy of the body. Its significance has heen pointed out especially by the ingenious investigations of Metschnikoff, Leber, and Bordet. These phagocytes act as scaven- gers, taking up and making away sometimes with blood debris, nuclear fragments, pigment, fat globules and all sorts of minute foreign particles with which they come in contact. The ingestion of such corpuscular elgmcnts is with them a simple process of feeding. The movement and approach of the phagocytes may be inducecl by a number of Stimuli, as warmtli or an acid. acting upon their own tactile or Chemical sensitiveness. In coming in contact with foreign particles they attempt to increase their surface of contact as much as possible [applying their protoplasm more and more about the surface of the particle, and thus eventually enveloping it in their own material] ; and are at- tracted by various chemical substances (chemotaxis). [It is but fair to add here that wliile the theory of chemotaxis, as a part of the general theory of “tropisms” or of blind automaton- like response of living tliings to external forces or attractions, finds wicle adherence among medical men and biologists, there are nevertheless otliers who do not accept such a view, the latter finding reason to believe that the manifestations which the former](https://iiif.wellcomecollection.org/image/b28130078_0038.jp2/full/800%2C/0/default.jpg)
