THE INTESTINAL PROTOZOA OF FROGS AND TOADS. 203 
Hisroric. 
I wish to give here only a general—and very brief— 
synopsis of the work which has been done upon the protists 
in the gut of the frog. I shall have to consider the various 
organisms in greater detail later, as I come to them. The 
subject is one of some interest, however, for it engaged the 
attention of some of the earliest microscopists. 
Probably the first man to discover the existence of Protozoa 
in the intestine of the frog was van Leeuwenhoek, who, in 
1683 (‘Omnia Opera’), described and figured “ animalcula 
in stercore Ranarum,”’ These ‘“animalcules” are generally 
supposed to have been Opalina intestinalis Hhrbg. Later, 
Leeuwenhoek carried his researches further, and was able— 
in 1702—to recognise three different protozoan “ animalcula 
in the excrements of frogs.’ The species were, in all pro- 
bability, Nyctotherus cordiformis Ehrbg., Opalina 
intestinalis Ehrbg., and another organism which was pro- 
bably Trichomonas or Trichomastix—“ Bodo ranarum” 
according to Ehrenberg. 
For more than a century subsequently the subject received 
only brief and occasional notice. But I may mention during 
this period the names of Bloch (1782) and Goze (1782) who 
both devoted themselvyes—more or less successfully—to the 
study of these ‘‘intestinal worms” (Opalina, etc.). It was 
not until 1838 that any considerable advance was made. In 
this year—a landmark in the history of protistology— 
appeared the great work of Ehrenberg (16). Here we find 
that the author was able to distinguish no less than eight 
different species of protists. I give these below, with their 
probable synonyms in use at the present day: 
1. Bodo ranarum Ehrenberg = Trichomonas or Tricho- 
mastix. 
2. Bodo intestinalis Ehrenberg .= Octomitus. 
3. Bursaria ranarum Ehrenberg .= Opalina ranarum. 
4. Bursaria intestinalis Ehren- 
berg. : : .= Opalina intestinalis. 
