362 POPULAR SCIENCE MONTHLY. 



malaria in the blood of persons suffering from intermittent fever. 

 Blood was drawn from the finger during the febrile attack and from in- 

 dividuals to whom quinine had not been administered. The demonstra- 

 tion was entirely satisfactory, and no doubt was left in my mind that I 

 saw living parasitic micro-organisms in the interior of red blood cor- 

 puscles obtained from the circulation of malarial-fever patients. The 

 motions were quite slow and were manifested by a gradual change of 

 outline rather than by visible movement. After a period of amoeboid 

 activity of greater or less duration, the body again assumed an oval or 

 spherical form and remained quiescent for a time. While in this form 

 it was easily recognized, as the spherical shape caused the light passing 

 through it to be refracted and gave the impression of a body having a 

 dark contour and a central vacuole; but when it was flattened out and 

 undergoing amoeboid changes in form, it was necessary to focus very 

 carefully and to have a good illumination in order to see it. The objec- 

 tive used was a Zeiss's one-twelfth inch homogeneous oil immersion. 



But, very properly, skepticism with reference to the causal relation 

 of these bodies to the disease with which they are associated was not re- 

 moved by the demonstration that they are in fact blood-parasites, that 

 they are present in considerable numbers during the febrile paroxysms 

 and that they disappear during the interval between these paroxysms. 

 These facts, however, give strong support to the inference that they are 

 indeed the cause of the disease. This inference is further supported by 

 the evident destruction of red blood corpuscles by the parasite, as shown 

 by the presence of grains of black pigment in the amceba-like micro- 

 organisms observed in these corpuscles and the accumulation of this in- 

 soluble blood pigment in the liver and spleen of those who have suffered 

 repeated attacks of intermittent fever. The enormous loss of red blood 

 corpuscles as a result of such attacks is shown by the ansemic condition 

 of the patient and also by actual enumeration. According to Kelsch, a 

 patient of vigorous constitution in the first four days of a quotidian in- 

 termittent fever, or a remittent of first invasion, may suffer a loss of 

 2,000,000 of red blood corpuscles per cubic millimeter of blood, and in 

 certain cases a loss of 1,000,000 has been verified at the end of twenty- 

 four hours. In cases of intermittent fever having a duration of twenty 

 to thirty days the number of red blood cells may be reduced from the 

 normal, which is about 5,000,000 per cubic millimeter to 1,000,000 or 

 even less. In view of this destruction of the red blood cells and the 

 demonstrated fact that a certain number, at least, are destroyed during 

 the febrile paroxysms by a blood parasite, which invades the cells and 

 grows at the expense of the continued haemoglobin, it may be thought 

 that the etiological role of the parasite should be conceded. But scien- 

 tific conservatism demands more than this, and the final proof has been 

 afforded by the experiments of Gerhardt and of Marchiafava and Celli — 



