PLATE XVIII. 



FIG. i. WIDAL'S REACTION. 



This fi-ure is given to show the bacillary clumps which form when the blood serum of a 

 p.uient sufn_nng from typhoid (ever is added to a living broth cultiue of the typhoid bacillus, 

 the phenomenon being known as Widal's reaction. 



In the case of the preparation figured, i part of blood serum was added to 19 ot a twenty- 

 four hours' (incubated) broth culture. The blood had been collected in a pipette and 

 allowed to clot ; a certain number of red corpuscles are admixed with the serum. 



The clumping or agglutination of the bacillus is readily observable under i-Ctri objective, 

 though the clump represented was drawn under i-i2th oil immersion, and is magnified about 

 TOGO times. 



The method of carrying out the test for the diagnosis of typhoid fever is ully given in 

 the text. 



FIG. 2. BACILLUS OF LEPROSY. 



The figure represents three highly vacuolated enclothelial cells from a lymphatic gland 

 secondarily infected in a case of leprosy of the tongue. The cells occurred along with others 

 of similar character in irregular groups scattered throughout the gland. The notable 

 vacuolation (regularly seen in such "leprous cells") is possibly due to an abundant 

 formation of digestive fluid secreted by the cell that it may destroy and utilise the bacilli. 

 Highly vacuolated cells at times hold extremely few bacilli, possibly as a result of such a 

 process of destruction. The bacilli mostly lie in the septa between or around the vacuoles, 

 though when the vacuole is not viewed in strict optical section they appear to lie within. 



The leprosy bacilli are slender, straight, or slightly curved rods, very uniform in breadth, 

 and fairly so in length, and they closely correspond in size and general character with those 

 of tuberculosis, as the latter are met with, e.g:, in phthisical sputum. They present a markedly 

 beaded appearance arising from protoplasmic segmentation. They give, again, the same 

 common staining reaction, in this resembling, moreover, the bacillus of Mnegma ; i.e., after 

 being dyed with carbol fuclisine the bacilli resist decolorisation in a 25 per cent, mixture 

 of sulphuric acid in distilled water. The smegrna bacillus is not infrequently present in the 

 urine of both sexes, and may be mistaken for that of tubercle. This error can be avoided by 

 examining the urine drawn off by catheter, the smegma bacillus being in this way excluded. 

 And to select one of many differential staining methods, though dyed with carbol fuchsine, 

 the colour of the smegma bacillus is discharged in a mixture of 20 per cent, nitric acid in 

 alcohol, whilst that of the tubercle bacillus is retained. For the reliable examination of 

 urine a centrifuge is indispensable. 



The sections of the leprous gland were stained for fifteen minutes (without heat) in carbol 

 fuchsine, passed through 25 per cent, sulphuric acid, washed in water and counterstained for 

 five seconds in a i per cent, aqueous solution of methyl blue, after which they were passed 

 through water, absolute alcohol, oil of cloves, and mounted, finally, in a solution of Canada 

 balsam in xylol. For the counterstaining of tissue methyl not methyler.e blue, is to be used ; 

 the latter is almost entirely removed by the subsequent immersion of the section in alcohol. 

 The counterstaining of cover-glass films of phthisical sputum is satisfactorily carried out by 

 means of an aqueous solution of methylene blue. (See the previous volume.) 



The Leprosy bacilli are not in all cases located within the cells of a tissue : they may lie in 

 a ground substance or gloea occupying the lymph spaces. 



