INTROD UCTION 13 



been found abundantly in silicious rocks of the Palaeozoic and 

 the Mesozoic, and are also identified with the clays and other 

 formations of the Miocene. Thus knowledge of these two orders 

 of Sarcodina, at least, is essential for the student of geology and 

 paleontology. 



The History of Protozoology 



Aside from the few large forms, Protozoa are unobservable 

 with the naked eye, so that we can easily understand why they 

 were unknown prior to the invention of the microscope. Antony 

 van Leeuwenhoek (1632-1723) is commonly recognized as the 

 father of protozoology. Grinding the lenses himself, Leeuwen- 

 hoek made more than four hundred microscopes, including one 

 which, it is said, had a magnification of 270 times. Among the 

 many things he discovered were various Protozoa. Between 

 1673 and 1703 he apparently observed Vorticella, Carchesium, 

 Stylonychia, Volvox, Opalina, Nyctotherus, Polystomella, etc. 

 Thus he was the first to see some of the well-known Protozoa. 



Leeuwenhoek was followed by Buonanni (1691), who ob- 

 served Colpoda; by Harris (1696), who discovered Euglena; 

 and by an anonymous author (1703), who described Euplotes, 

 Vorticella, and Paramecium. In 1718 there appeared a treatise 

 on microscopic organisms by Joblot, in which the author em- 

 phasized the non-existence of abiogenesis by using boiled hay- 

 infusions in which no Infusoria developed without exposure to 

 the atomosphere. This experiment confirmed that of Redi who, 

 twenty years before, had made his well-known experiments by 

 excluding flies from decomposing meat. Trembly (1745) studied 

 division in some Ciliata, including probably Paramecium. 

 Noctiluca was first described by Baker (1753). 



Rosel (1755) observed an amoeba, possibly Amoeba proteus 

 or an allied form, which he called "die kleine Proteus," and also 

 Vorticella, Stentor, and Volvox. Ledermiiller is said to have 

 coined the term "Infusoria" in 1763 (Butschli). By using the 

 juice of geranium, Ellis (1770) caused the extrusion of the "fins" 

 (trichocysts) in Paramecium. Eichhorn (1783) observed the 

 heliozoan, Actinosphaerium, which now bears his name. 

 O. F. Miiller described Ceratium a little later and published two 

 works on the Infusoria (1786). Although he included unavoid- 



