DISCOVERY OF THE PROTOZOA 105 



discovery and the progress of knowledge in reference to them 

 will be in place in this chapter. 



Discovery of the Protozoa. — Leeuwenhoek left so little 

 unnoticed in the microscopic world that we are prepared to 

 find that he made the first recorded observations upon these 

 animalcula. His earliest observations were communicated 

 by letter to the Royal Society of London, and were published 

 in their Transactions in 1677. It is very interesting to read 

 his descriptions expressed in the archaic language of the time. 

 The following quotation from a Dutch letter turned into 

 English will suffice to give the flavor of his writing: 



"In the year 1675 I discovered living creatures in rain- 

 water which had stood but four days in a new earthen pot, 

 glazed blew within. This invited me to view the water with 

 great attention, especially those little animals appearing to 

 me ten thousand times less than those represented by Mons. 

 Swammerdam, and by him called water-fleas or water-lice, 

 which may be perceived in the water with the naked eye. 

 The first sorte by me discovered in the said water, I divers 

 times observed to consist of five, six, seven or eight clear 

 globules, without being able to discover any film that held 

 them together or contained them. When these animalcula, 

 or living atoms, did move they put forth two little horns, 

 continually moving themselves; the place between these 

 two horns was flat, though the rest of the body was roundish, 

 sharpening a little towards the end, where they had a tayle, 

 near four times the length of the whole body, of the thick- 

 ness (by my microscope) of a spider's web; at the end of 

 which appeared a globule, of the bigness of one of those 

 which made up the body; which tayle I could not perceive 

 even in very clear water to be mov'd by them. These little 

 creatures, if they chanced to light upon the least filament 

 or string, or other such particle, of which there are many in 

 the water, especially after it has stood some days, they stook 



