ijo Appendix. 



the mode of their generation was quite fully explained, at least 

 for all but the very lowest species, and that generally scientific 

 men held that the question was put to rest by the decisive experi- 

 ments of Schultze and Schwann, just alluded to. The 3d epoch 

 dates from the year 1858, when the question was reopened in 

 Paris for special reasons connected with the study and theory of 

 evolution. In this, the present epoch, the whole battle ground 

 is within the domain of infusorial life, and although, by the 

 majority of scientists, the victory thus far is conceded to the 

 advocates of biogenesis, or life from preexisting life, a few still 

 courageously contend for the opposing theory abiogenesis life 

 without preexisting life, or life from inorganic matter alone. 



\st Epoch. During this period a belief in the spontaneous 

 generation of many animals was universal. Even Aristotle, who 

 may be considered to represent the highest type of the scientific 

 culture of the day, divided animals, with reference to their mode 

 of production, into two classes. The one was derived by suc- 

 cession from preexisting parents, life being transmitted either by 

 the production of living young resembling the parents, or through 

 the hatching of eggs, or, as in many insects, by grubs or larvae. 

 In the other class no such connection could be traced, and hence 

 they were considered to originate spontaneously from "the for- 

 tuitous concourse " of inorganic materials, from the slime or 

 ooze at the bottom of the sea, or from the decomposing remains 

 of other animals. Thus the shell-fish, such as clams and oysters ; 

 the sea-nettles and sponges ; the maggots that invariably swarm 

 after a time in dead meat ; very many of the smaller insects that 

 appear so suddenly; grubs, moths, eels and many other small 

 fishes, are enumerated as originating in this way. The idea of 

 decomposition and recomposition of organic 'atoms was a favor- 

 ite one, not only during antiquity, but down through the middle 

 ages. It finds its best expression, perhaps, in Aristotle's well 

 known formula, Corruptio unius est generatio alterius. These 

 crude beliefs were not confined to the Greek scientists alone, but 

 continued even down to the middle of the seventeenth century, 

 at which late day Kircher, the learned Jesuit, declared that to 



