202 peesident's address. 



creatures of higher grades may now and then likewise he found. 

 The study of these organisms, long a favourite one with micros- 

 copists, received some thirty years ago a fresh impetus from the 

 researches of Dr. Charlton Bastian, who believed that he had 

 demonstrated that monads might and did constantly in such 

 solutions arise de novo by a process of so-called " spontaneous 

 generation," apart altogether from the presence in the fluid of 

 any pre-existing germs. It is needless to describe here the 

 details of Dr. Bastian's experiments. He exposed solutions or 

 infusions of various kinds to a boiling temperature in glass flasks, 

 which during the boiling process were hermetically sealed, and 

 in many cases he found that notwithstanding these precautions 

 living organisms made their appearance in the flasks. Whether 

 the most rigid precautions were always used we need not stop 

 to enquire, but one fact unknown at that time, though now 

 sufficiently established, is enough to vitiate the whole series of 

 experiments, — namely, that the germs of some of these monads, 

 if not the adult creatures themselves, may be submitted for a 

 considerable time to a boiling temperature and yet retain their 

 vitality. Moreover, Professor Tyndall has shewn, by a series 

 of well devised and beautiful experiments, that previously steril- 

 ized infusions may be kept from developing life, even though 

 exposed to a current of air, by the simple expedient of filtering 

 the air of its floating impurities. So that, while it cannot be 

 said that "spontaneous generation" has been proved to be im- 

 possible, it is quite certain that the balance of evidence is in 

 favour of such a belief, and that the experiments which have 

 been thought to weigh greatly in the opposite direction are so 

 clouded with doubt as to render them of comparatively small 

 account. There is, in fact, nothing in the science of to-day 

 contradictory of the old axiom omne vivum ex vivo:^' It consti- 



* Such, certainly, is the conclusion to which experiment leads us. Whether, from a 

 purely speculative standpoint, the same conclusion is tenable may admit of doubt. 

 The origin of life is, for the present, involved in mystery : but is there any valid reason 

 for belief that the conditions under which life originated, and the causes of that origin, 

 are now non existent? All living matter consists of a combination of inorganic 

 elements, and must in some way have been built up in its beginning out of those ele- 

 ments; a like synthesis is going on constantly under our eyes through the agency of 

 already organised beings:— does it ever go on, as it must once have done, apart from 

 that agency V The last word is far from having been said on that question. 



