240 BIOGENESIS AND ABIOGENESIS VIII 



on to ask how far the growth of science justifies 

 his other hypothesis of Xenogeiiesis. 



The progress of the hypothesis of Biogenesis 

 was triumphant and unchecked for nearly a 

 century. The application of the microscope to 

 anatomy in the hands of Grew, Leeuwenhoek, 

 Swammerdaxn, Lyonnet, Vallisnieri, Reaumur, and 

 other illustrious investigators of nature of that 

 day, displayed such a complexity of organisation 

 in the lowest and minutest forms, and everywhere 

 revealed such a prodigality of provision for their 

 multiplication by germs of one sort or another, 

 that the hypothesis of Abiogenesis began to 

 appear not only untrue, but absurd ; and, in the 

 middle of the eighteenth century, when Needham 

 and Buff on took up the question, it was almost 

 universally discredited. 1 



But the skill of the microscope makers of the 

 eighteenth century soon reached its limit. A 

 microscope magnifying 400 diameters was a chef 

 d'oeiivre of the opticians of that day ; and, at the 

 same time, by no means trustworthy. But a 

 magnify ing power of 400 diameters, even when 



1 Needham, writing in 1750, says : 



" Les naturalistes modernes s'accordent unaninement a etablir, 

 comma nne verite certaine, que tonte plante vient de sa semence 

 specitlque, tout animal d'un ceuf ou de quelque chose d'analogue 

 preexistant dans la plante, ou dans 1'anirnal de ineme espece qui 

 1'aproduit." Nouvclles Observations, p. 169. 



" Les naturalistes ont generalemente cm que les animaux 

 microscopiques etaient engendres par des oeufs transported dans 

 Fair, ou deposes dans des eaux donnantes par des insectes 

 volans." Ibid. p. 176. 



