IMMUNITY AGAINST MICROBES. 445 



verted into a homogeneous, highly-refracting mass, consisting 

 of sheaths of the dead parasites. At the same time, however, 

 the giant-cells and epithelioid cells suffer in the fight, their 

 nuclei become granular, the protoplasm liquefies, and so finally 

 parts of the tumour consist of actinomycosis — few of which 

 show any signs of life — and masses of dead amoeboid cells. 

 In other parts everything is dead, and nothing is left but the 

 dead bodies of the parasites and pus-cells. Strangely enough 

 when this is the case, the lymphoid cells in the surrounding 

 parts do not appear to make the slightest attempt to take the 

 dead particles into their interior, but neglect them in favour 

 of the living leucocytes and fungi in their neighbourhood — -a 

 proof, if any were wanting, that phagocytes do not eat up 

 everything they come across, but exert a distinct choice. 



In actinomycosis, therefore, as in tubercle, the amoeboid cells 

 which enter into the formation of the '^pathological granuloma^' 

 are fighting cells which actively destroy the invading parasites. 



Although many facts have accumulated to give us some idea 

 as to what happens when micro-organisms are introduced into 

 the subcutaneous tissue, our knowledge of the processes fol- 

 lowing on their forcible introduction into the blood is still 

 extremely meagre. 



According to Wyssokowitch^ micro-organisms are not des- 

 troyed in the blood, but remain for a certain length of time in 

 the organs, more particularly in the lymphatic glands, the 

 medulla of bones, and the spleen. Wyssokowitch found them 

 in the endothelial cells of blood-vessels. Micro-organisms, ac- 

 cording to the same author, are not eliminated by the urine, 

 unless through some lesion of the kidney (diapedesis, rupture 

 of vessel, abscess, infarctus, &c.) ; Berlioz ^ has arrived at the 

 same conclusion. That this, however, is not an absolute rule 

 has been proved by Charrin^ and myself.* 



' Wyssokowitch, ' Zeitschrift f. Hygiene,' 1886, T. i. Heft 1, p. 45. 

 - Berlioz, 'These de Paris/ 1888. 

 3 Charrin, * La Maladie Pyocyauique.' 



"• Armand Ruifer, ' Experimental Investigation into the Nature of the Dis- 

 ease produced by the Inoculation of the Bacillus pyocyaneus.' 



