ADDRESS. Ixxix 



association, of its constitxient organic molecules, wliich are then sot free as 

 infusorial animalcules. 



It will be perceived that this doctrine is by no means identical ^vith 

 Abiogenesis, with which it is often confounded. On this hypothesis, a piece 

 of beef, or a handful of hay, is dead only in a limited sense. The beef is 

 dead ox, and the hay is dead grass ; but the " organic molecules " of the beef 

 or the hay are not dead, but are ready to manifest their vitality as soon as 

 the bovine or herbaceous shrouds in wliich they are imprisoned are rent by 

 the macerating action of water. The hypothesis therefore must be classified 

 under Xenogenesis, rather than under Abiogenesis. Such as it was, I think 

 it will appear, to those who will be just enough to remember that it was pro- 

 pounded before the birth of modern chemistry and of the modern optical arts, 

 to be a most ingenious and suggestive speculation. 



But the great tragedy of Science — the slapng of a beautiful hypothesis 

 by an ugly fact — which is so constantly being enacted under the eyes of phi- 

 losophers, was played, almost immediately, for the benefit of Bufi'ou and 

 Needham. 



Once more, an Italian, the Abbe SpaUanzani, a worthy successor and repre- 

 sentative of Eedi in his acuteness, his ingenuity, and his learning, subjected 

 the experiments and the conclusions of Keedham to a searching criticism. 

 It might be true that Needham's experiments yielded results such as he had 

 described, but did they bear out his arguments ? Was it not possible, in the 

 first place, that he had not completely excluded the air by his corks and 

 mastic ? And was it not possible, in the second place, that he had not suf- 

 ficiently heated his infusions and the superjacent air ? SpaUanzani joined 

 issue with the English naturalist on both these pleas ; and he showed that 

 if, in the first place, the glass vessels in which the infusions were contained 

 were hermetically sealed by fusing their necks ; and if, in the second place, 

 they were exposed to the temperature of boiling water for three-quarters of 

 an hour *, no animalcules ever made their appearance within them. It must 

 be admitted that the experiments and arguments of SpaUanzani furnish a 

 complete and a crushing reply to those of J^Ieedham. But we aU too often 

 forget that it is one thing to refute a proposition, and another to prove the 

 truth of a doctrine which implicitly, or expUcitly, contradicts that proposition ; 

 and the advance of science soon showed that though ISTeedham might be quite 

 wrong, it did not foUow that SpaUanzani was quite right. 



Modern Chemistiy, the birth of the latter half of the eighteenth century, 

 grew apace, and soon found herself face to face with the great problems 

 which Biology had vainly tried to attack without her help. The discovery 

 of oxygen led to the laying of the foundations of a scientific theory of re- 

 spu-ation, and to an examination of the marveUous interactions of organic 

 substances with oxygen. The presence of free oxygen appeared to be one 

 of the conditions of the existence of life, and of those singular changes in 

 organic matters which are known as fermentation and imtrefaction. The 

 question of the generation of the infusoiy animalcules thus passed into a 

 new phase. For what might not have happened to the organic matter of the 

 infusions, or to the oxygen of the air, in SpaUanzani's experiments ? What 

 security was there that the development of life which ought to have taken 

 place had not been checked, or prevented, by these changes ? 



The battle had to be fought again. It was needful to repeat the expe- 

 riments under conditions which would make sure that neither the oxygen 



* See SpaUanzani, ' Opere,' vi. pp. 42 & 51. 



