258 -Appendix. 



cules. In 1764 Wiesberg gave them the name which they now 

 bear ; this designation was made from the fact that they are al- 

 ways found in stagnant water and in infusions of both animal and 

 vegetable materials after short standing. Subsequently they were 

 studied by many observers, but it is to Ehrenberg* and Dujar- 

 din** that we are indebted for the most systematic description of 

 them, and their great works figure hundreds of varieties. The 

 almost illimitable numbers, the great diversity of form and of 

 organization, as well as the combined bulk of these microscopic 

 beings are almost beyond conception. We now know that there 

 are geological deposits of great size in different portions of the 

 earth's crust that consist almost exclusively of the calcareous 

 and silicious shells of these minute beings. Indeed Ehrenberg 

 himself regarded them '* as forming by far the greatest number 

 and perhaps also the largest mass of living animal organisms on 

 the surface of the globe"f The rapidity of their development 

 is something wonderful, and being also infinitesimal in size their 

 mode of procreation was beyond the reach of the microscopes of the 

 day, and it is no surprise to learn that the old doctrine of spon- 

 taneous generation was again invoked to account for their origin. 

 This was done in 1748 by Needhamfff and BufTon, who " led 

 by certain theoretical considerations doubted the applicability of 

 Redi's hypothesis to the infusorial animalcules, and Needham 

 endeavored to bring* the question to an experimental test."ff 

 Taking the juices of meats which had been extracted at a high 

 temperature he enclosed them in glass vials, also previously heat- 

 ed, corked them tightly and set them aside to cool. After a few 



* Die Infusionsthierchen, als vollkommene Organismen. Leipzig, 1858. 

 ** Histoire Naturelle des Zoophytes Infusoires. Paris,, 1841. 

 t D ALTON : loc. cit. p. 127. 

 ft HUXLEY : loc cit. 



ttt JOHN TUBERVILLE : an English naturalist, 1713-1784. He was edu- 

 cated in the Roman Catholic faith and became a priest in that church, his life 

 being mostly spent on the Continent. He was Director of the Academy of 

 Maria Theresa, at Brussels. He devoted himself to scientific investigations 

 in connection with his work in teaching, and published many papers. His 

 principle work was a Treatise on Generation, published in French, the year 

 previous to his death. 



