THE PRESENT STATE OF KNOWLEDGE OK THE AMOEBAE II 



one another zoologically : and it had been proved, by Casagrandi and 

 Barbagallo, that the intestinal amoebae have nothing to do with the 

 free-living species, from which they differ both morphologically and in 

 the character of being uncultivable in artificial media. It is truly 

 astonishing, in reading the works on the intestinal amoebae of man, 

 such as Behla's (1898), and the larger medical and zoological treatises 

 published at the end of the last and the beginning of the present century, 

 to observe the blindness which appears to h:ive descended upon everj'- 

 body who studied this subject at this period. Instead of illumination, 

 darkness followed ; and the twentieth century began with a period of 

 nearly a dozen years of chaos. 



For this period of confusion Schaudinn was, in my judgement, 

 chiefly responsible. Notwithstanding his great services to the science 

 of protozoology in other respects, his influence upon the present subject 

 was almost wholly bad. His work, published in 1903, produced a pro- 

 found effect, though it was merely a brief preliminary statement of his 

 views — dogmatic, full of errors, unillustrated ; and his conclusions, had 

 they been presented by any other worker, would probably not have 

 been accepted without further evidence. There was, indeed, but one 

 fundamental point in which he was not mistaken — his assertion that 

 there are two different amoebae, one pathogenic and the other harmless, 

 inhabiting the human bowel : and nobody who has read the works of 

 earlier observers can give Schaudinn much credit for this "discovery," 

 in which he had been forestalled repeatedly. Nevertheless, the fact 

 remains that when Schaudinn said it, everybody realized its truth ; 

 whereas the words of earlier observers fell upon deaf ears. Schaudinn's 

 " life-histories " of the two forms were almost entirely wrong. Some 

 of his observations and experiments are, indeed, so incredible* that it is 

 difficult to briieve that they were not sheer inventions. Certain it is, at 

 all events, that no competent worker will ever repeat them. In his 

 revision of the nomenclature of the intestinal amoebae he was equally 

 unfortunate, and for his errors of judgement we still suffer. 



Another cause of the arrest of progress in this subject at the 

 beginning of the century was undoubtedly the work of Musgrave and 

 Clegg (1904, 1906), carried out in the Philippines. These workers 

 upheld the thesis that " all amebas are or may become pathogenic." 

 Their chief reason for believing this, apparently, was their inability to 

 distinguish one species of amoeba from another. For them all amoebae 

 were alike. They appear to have been almost uninfluenced by the 

 earlier work of others, and to have thought it unnecessary to study 

 protozoology or cytological methods. Mixing up all species of amoebae 

 indiscriminately, and studying none of them properly, they soon reached 

 the conclusion that " the whole of the surface flora of the Philippine 

 Islands carries a large number of these parasites [i.e., ' amoebae ' 

 generally]. Some of which, at least, belong to the class [= species] 

 which produces disease in human beings." The importance they 

 attributed to morphology can be gauged by their statement that "at 

 the present time no value can be attached to it." Upon zoologists 

 generally the expression of such views could naturally produce but 



* See, for example, his amazing experiment by which he proved that JS. histolytica 

 forms minute spores capable of surviving, in a condition infective to cats after complete 

 desiccation. This experiment is, to me, still quite inexplicable. 



