THE RELATIONS OF MICRO-ORGANISMS TO DISEASE. 163 



But notwithstanding the safeguards of the body against the access of 

 micro -organisms, these do frequently enter; this may occur in severe in- 

 juries to the skin or mucous membranes or through very slight and un- 

 noticed abrasions or other solutions of continuity. Entrance may be 

 gained to the tissues through the minute ducts of the sebaceous or sweat 

 glands ; from the mouth, tonsils, gastro-intestinal canal 1 and the respi- 

 ratory passages and surfaces, either with or without obvious injuries to 

 the investing epithelia. The role of insects in the conveyance of infec- 

 tious agents is of great importance. 11 Micro-organisms may enter the 

 body during intrauterine life. 3 



When in one way or another bacteria or other germs have entered 

 the tissues, they may encounter a series of obstacles to their spread or 

 continuance as well as to their proliferation there, even should the gen- 

 eral nutritive conditions be favorable. In the first place the lymph- 

 nodes frequently filter out of the tissue fluids micro-organisms which 

 have entered them, holding them back from the general circulation or 

 destroying them. 4 The power of certain of the body fluids and of living 

 cells under favorable conditions to kill and dispose of germs, should 

 these gain entrance through injuries or other structural lesions or func- 

 tional disturbance in the barriers, is of great importance and will be re- 

 ferred to again. The elimination of micro-organisms from the body 

 through its secretions, 5 such as urine, bile, milk, sweat, saliva, etc., is a 

 matter of great significance, but one upon which the scope of this book 

 does not permit us to enter. 6 



The view has been recently advanced that with no apparent lesion or 



1 For bibliography concerning the permeability of the gastro-intestinal canal for 

 bacteria refer to p. 560. 



*Nuttall, Johns Hopkins Hospital Reports, vol. viii., p. 1, 1900. For studies of 

 flies as carriers of typhoid see Hamilton, Jour. Am. Med. Assn., vol. xl., February 28th, 

 1903, p. 576 \ f also Martin, Public Health, August, 1903. 



3 For a resume of studies on the congenital transmission of infectious agents see 

 "Wassermann , in Kolle and "Wassermann's "Handbuch der Mikroorganismen," Bd. i., p. 

 380, Bibl. 



4 Manfredi, Virch. Arch., Bd. civ., p. 335, 1899, for a study of the germicidal and 

 other action of lymph-nodes; also Bezanfon and Labbe, Arch, de Med. expe"rimentale et 

 d'Anat. path., t. x., p. 389, 1898. 



6 Consult Sherrington, "Experiments on the Escape of Bacteria with Secretions," 

 Journal of Pathology and Bacteriology, vol. i., p. 258, 1893; Biedl and Kraus, Arch. f. 

 exp. Path., Bd. xxxvii., p. 1, 1895, Bibl.; Hintze and Liibarsch, "Ergebnisse der allg. 

 Aetiologie der Meuschen- und Thierkrankheiten," 1896, p. 287. For study of disap- 

 pearance of bacteria from the body, see Pawloimky, Zeits. f. Hygiene und Infect. Krank- 

 heiten, Bd. 33, p. 261 ; see also ref. to Asch, p. 624. 



6 For a suggestive summary of the various factors which are or may be concerned 

 in the protection of the body against the invasion and action of micro-organisms, see 

 Meltzer, "Physiological Methods of Protection of the Body against Bacteria," Trans, of 

 the Congress of American Physicians and Surgeons, vol. v., p. 12, 1900; see also ref. 

 to Wassermann above. 



See also for the importance of a lesion in animal tissues for the lodgment and mul- 

 tiplication of bacteria within it, C/teesman and Meltzer, Jour. Exp. Med., vol. iii., p. 

 533 ; also on the significance of granulation tissue in wound infection, Afanassieff, Zieg- 

 ler's Beitrage, Bd. xxii., p. 11, 1897; also Cobbelt and Melsome, Centralbl. f. Path., Bd. 

 ix., p. 827, 1898, Bibl. ; also Jurgelunas, Ziegler's Beitrage, Bd. xxix., p. 92, 1901, Bibl. 

 For the role of the spleen in infection and intoxication, see Courmont and Duff an, Arch, 

 de Med. exp., May, 1898, p. 431, and Nicolas and Bean, Jour, de Phys. et Path, gen., 

 t. iii., 1901, p. 68. 



