28 MICRO-OEGANISMS AS PARASITES, 



the cells of C/iara were full of dead and dying bacteria ; the plant 

 had had a hard fight, but was victorious. To return to Metsch- 

 nikoff's experiments, this time with a vertebrate animal. The 

 leucocytes in the lymphatics of a frog not only devour anthrax bacilli, 

 but called in other leucocytes to their aid. Illustrations of the 

 whole process, which occupied 40 minutes, will be found in Mr. 

 Bland Sutton's Lectures on Patliology. In Botryllis Metschnikoff 

 found a spirochxta closely resembling that of relapsing fever, 

 and a small bacillus resembling the lepra bacillis. Both these 

 organisms were pursued by leucocytes, ingested and absorbed by 

 them. Some leucocytes perished in the attempt. In the same 

 way Koch found bacillus anl/iracis, and the bacillus of scpticoemia 

 in the mouse, enclosed by white blood-cells. Throughout the 

 whole animal kingdom these cells use their ingestive powers for 

 destroying bacteria and similar organisms. 



These amoeboid cells exhibit a very curious power of throwing 

 out pseudopodia, which unite with similar protrusions from 

 neighbouring amoeboid cells, until a considerable mass of proto- 

 l^lasm is formed by their influence. Such a mass of fused cells is 

 known as a Plasmodium. Metschnikoff has watched their formation 

 in a transparent mollusc F/iyllirhde, around masses of carmine 

 granules. He writes : " The cells came one by one to each lump, 

 and flattened themselves upon it, fusing with neighbouring cells as 

 these arrived. In this way arose plasmodia of difterent sizes, some 

 even visible to the naked eye, wJiicJi might be compared to the 

 giant-cells of vertebrates." He adds, " In all cases in which I 

 have found giant-cells in invertebrates, they have arisen round 

 foreign bodies, and always by fusion of separate cells." Mr. 

 Bland Sutton remarks, " In such diseases as tubercle, leprosy, 

 and the tuberculosis of the fowl and ox, there is a peculiar cell 

 to be detected, the giant-cell ; and in cases where bacilli have been 

 discovered in the tissues, these micro organisms have been found 

 to occupy the interior of the giant-cells, sometimes in enormous 

 numbers." 



This view is remarkably confirmed by Koch, who says, in his 

 paper on the Etiology of Tuberculosis — " Direct observation seems 

 to show that on their first entry into the system, the tubercle-bacilli 

 are seized upon and carried away by wandering cells. If an 



