18 



in spite of two or three large injections daily: strong solutions are 

 often too irritating to be practical or, in the case of susceptible 

 subjects, may reduce the patient to a state of chronic cinchonism 

 by the absorption of the drug from the ])owel. This last condition 

 is more apt to occur where the practice prevails of giving several 

 concentrated injections a day. 



The stronger antiseptics are likely to be irritating or dangerous 

 on account of their toxic properties. 



The perfection of the technique of growing the amcebfe in pure 

 strains in symbiosis with a single variety of bacteria attained by 

 Mnsgrave and Clegg has made it possible to observe with a con- 

 siderable degree of accuracy the action of chemical substances on 

 the amoeba?, and it is with the results of a series of such experiments 

 conducted by myself in the Biological laboratory of the Bureau of 

 Government Lal)oratories during December, 1904, and January, 

 1905, that this report is concerned. 



The standard amoelm used in these tests is described as follows 

 by ^Musgrave and Clegg in Bulletin No. IS. Biological Laboratory, 

 of the Bureau of Government Laboratories, published in October, 

 1901 : 



Amoeba 11524 was isolated from a dysentery stool. The patient, an 

 American nurse, had been suffering with intestinal amoebiasis (amoebic 

 dysentery) for about one year and amoebae had repeatedly been found in 

 her stools during that time. * * * xhe course of the disease was 

 a iisual one, with very chronic tendencies and with frequent, and some- 

 times quite severe, exacerbations. Our first cultures were made during 

 such an exacerbation and at a time when there could be no reasonable 

 doubt as to the correctness of the diagnosis. * « * Growth was found 

 to be very satisfactory for a long time on a medium composed of 2 

 per cent agar and one-half per cent beef extract { 1 per cent alkaline ) , 

 the development decreasing only when a marked diminution in the num- 

 ber of bacteria, which is usual with this medium, occurred. Micro- 

 scopically this protozoan as obtained from culture is indistinguishable 

 from those seen in the stools of the patient, and it is a true dysen- 

 teric amoeba. Its measurements in the round stage in the stool were 

 25 to 35 /t, and those in the cultures generally correspond with these 

 figures, but they varied greatly, owing no doubt to enviromuent and the 

 phase of the life cycle at the time of the examination. In our collection 

 there now are cultures of this amoeba which were started from a single 

 parasite. They are in j)ure culture with four diff'erent bacteria. * * * 

 B. coli, Sj)r. cholera' and two different pigment-producing saprophytes. 

 The protozoa grow well with all these organisms, and, by methods already 

 given, have been changed from one to the other, and vice versa. 



In one instance, dysentery in man followed the ingestion of three gelatin 



