24 THE AMOEBAE LIVING IN MAN 



frequent presence of red corpuscles in the cytoplasm, and the striking 

 activity of the organism, are all noted. In their account of all these 

 characters Quincke and Roos confirmed the observations of Losch, 

 Kovacs, and other early workers. But in addition, they discovered 

 the cysts of the parasite in the stools of their patient. They are 

 described as rounded, refractile structures with a thin but definite 

 wall, smaller than the active amoebae, and measuring 10-12 /x in 

 diameter. By means of careful experiments they proved that a cat 

 can be infected, and acquire amoebic dysentery with characteristic 

 intestinal lesions, by causing it to swallow the cysts, or by injection of 

 the active amoebae pt'/- <^/zw77/. All these characters were emphasized as 

 distinctive of the amoebae associated with dysentery in man : for they 

 found that the other amoebae which they studied (in reality E. coli) 

 differed in all the characters noted. They were sluggish, contained 

 ingested foreign bodies, but never red corpuscles, formed larger cysts 

 (16-17//-) with a thicker wall, and were non-infective and non-pathogenic 

 for cats. From their observations they drew the conclusion that man 

 acquires his infection with the dysentery amoeba by swallowing its cysts 

 — as they had shown to be possible in the case of the cat. The only 

 thing of any importance that Quincke and Roos failed to do was to 

 investigate the cytological details of the amoebae and their cysts. They 

 merely noted that the latter contain " nucleus-like structures," but they 

 did not study these properly nor count them. Roos's figures show cysts 

 with one or two nuclei (indistinct in some), and indications of chromatoid 

 bodies. In the matter of nomenclature they were unfortunate; for 

 though they rightly identified their pathogenic amoeba with Losch's 

 " Amoeba coli," they wrongly proposed to change its name to "Amoeba 

 coli felis," on account of its pathogenicity for the cat. 



The dysentery amoeba was restudied and redescribed by many workers 

 in the following decade, but nothing material was added to our knowledge 

 of it. Jurgens (1902) confirmed the earlier observations on the amoebae, 

 and Schaudinn (1903) renamed them. But neither of them studied the 

 cysts again, or understood the life-history of the organism. Schaudinn, 

 indeed, added a wholly incorrect account of its development, far behind 

 that of Quincke and Roos. He failed to find the cysts, and substituted a 

 highly imaginative account of " sporulation " in place of encystation.* 



In the very same year that Schaudinn's erroneous statements made 

 their appearance, a real discovery was made by Huber (1903) : but so great 

 was the authority of Schaudinn, that Huber's work was — and is — almost 

 completely ignored. Huber (1903) confirmed the observations of 

 Quincke and Roos. He studied a typical case of amoebic dysentery, he 

 saw the amoebae and their cysts, and he infected cats with the former per 

 rectum and with the latter per os. He added the important observation 

 that the cysts contain i, 2, or 4 nuclei, but never more, and also chromatin 

 masses and blocks, and can thus be distinguished from the cysts of the 



* According to Schaudinn, E. histolytica does not encyst but forms resistant spores, 

 3-7 M in diameter. These are described as being formed by a kind of "budding," 

 which is now generally supposed to have been a degenerative fragmentation. Craig 

 (1908)" confirmed" this account, and published figures of the stages: but notwith- 

 standing the circumstantial evidence brought forward by both these workers, I am 

 unable to decide what these "spores" really were. Craig has since recanted, but he 

 has not wholly explained his previous findings. 



