598 THE POPULAR SCIENCE MONTHLY. 



though he himself, with all this light, did not attain to the truest con- 

 ception of life, he nevertheless broke ground for those who afterward 

 were to do so. 



In more recent times biology has been enriched with an enormous 

 amount of facts for which we are indebted to the labors of natural- 

 ists, or even of mere breeders, as also to the labors of anatomists and 

 clinicians, but, above all, to researches in experimental physiology, 

 wherein the application of physical-science methods to the discovery 

 of the laws of vital phenomena has been attended with brilliant suc- 

 cess. Amid the extreme complexity of these phenomena it was diffi- 

 cult to perceive the relations of succession which unite them, and to 

 establish positive series. But when men of science refused any longer 

 to content themselves with observing them as they occur spontane- 

 ously, and began to vary them by calling in the action of special 

 agents, then modifications were produced, the true causes of which 

 were easily recognized. As in the study of inorganic bodies we 

 learned the laws of their actions and combinations by seeking to find 

 out with the aid of reagents which are, in fact, special modifiers 

 the way in which they behave under circumstances that are well 

 known, being fixed beforehand by the observer ; so, in the study of 

 living bodies, the introduction of experimentation which alters, ac- 

 cording to a plan determined beforehand, the conditions under which 

 the functions of life are to be performed, has enabled us to perceive, 

 with an exactitude previously unknown, tlie organic properties under- 

 lying these functions. Even in embryogeny, a science which once 

 seemed to belong to the domain of simple observation, it has been 

 possible, by way of experimentation, to gain results which shed some 

 light upon teratology. The employment, in observation, of instru- 

 ments of precision, and in particular of registering apparatus, and of 

 all those processes which suppress causes of error resulting from the 

 personal peculiarities of the observer, gives to the results of research 

 a degree of certitude which renders indisputable facts properly so 

 called, the only question that remains being as to whether these re- 

 sults have been rightly or wrongly interpreted. In addition to an 

 immense amount of unquestionable facts, in addition to a knowledge 

 of the elementary properties of organic tissues and an acquaintance 

 with the special laws which represent the action of these tissues in 

 presence of these modifiers, this general result has followed the con- 

 quests of biology, namely, that living bodies are now known to be 

 subject to the self-same laws which govern inorganic bodies, and that, 

 under the hand of the experimenter, the course of things within the 

 tissues is precisely the same as without the tissues ; that in the labo- 

 ratory the elements of living bodies, like those of inanimate things, 

 have their own way of affecting the mind that observes them that is 

 to say, they possess fixed essential properties which can be determined ; 

 and what remains yet to be known is, above all, the mode in which 



