252 MICROBES AND TOXINS 



the lymphoid organs : even when the bacillus had been found 

 in the urine and in the red eruption spots on the skin it was 

 still thought that it only exceptionally entered the blood. But 

 when cultures were regularly made from the blood of typhoid 

 patients it was perceived that the typhoid bacillus is present 

 there during the whole febrile period of the disease and again 

 during relapses : in typhoid fever, therefore, the acute enteritis 

 is complicated by a blood infection, a septicaemia. 



The examination of the faeces is regularly performed in the 

 diagnosis and prophylaxis of cholera, typhoid fever, and 

 dysentery, particularly in order to detect germ-carriers. Also 

 in the stools are sought the eggs of worm parasites and of 

 ankylostoma and amoebse. The bacteriological examination 

 of faeces is becoming more and more common in proportion 

 'as our knowledge of the intestinal flora is increasing; the 

 composition of this flora is a guide to the state of digestion and 

 nutrition, and aids the physician in his choice of a diet, 

 especially in infants, who are so often threatened by infections 

 of the alimentary canal. 



Indirect Diagnostic Methods. 



Even when no microbe is found in it, the blood may furnish 

 diagnostic proofs from its leucocytic formula. 



Cytodiagnosis (Widal) depends on the examination of the 

 cells floating in pleural effusions or cerebro-spinal fluids. 

 Different cells are found in a pleurisy due to the bacillus 

 tuberculosis and in one due to heart disease. Cytodiagnosis 

 of the cerebro-spinal fluid is an indirect diagnostic method in 

 certain tuberculous and syphilitic affections. 



Biological Methods : Agglutination. 



The first clinical sero-diagnostic method was discovered by 

 Widal. 



When a drop of a broth culture of the typhoid bacillus is 

 looked at under the microscope, the bacteria are seen actively 

 ■motile; isolated from each other and dispersed regularly 



