350 COMPARATIVE ANATOMY 



as a matter of fact, that furnishes us nothing certain, and we turn 

 to ontogeny and to anatomy, granting more value to one kind of 

 argument or to the other, according to the case, without any fixed 

 rule. In fact, we bring together all that we know concerning the 

 organs whose homology is in dispute, and we proclaim homology 

 when we find between these organs a sufficient conformity of char- 

 acteristics. In general, we interpose the condition that this homo- 

 logy shall not oppose the idea, very vague, very hypothetical, very 

 individual, which we may have concerning the phylogenetic deriva- 

 tion of the organs under consideration; but in many. cases we for- 

 get this, and are guided by the unavowed conception of an abstract 

 type constructed according to anatomical characteristics of every 

 order. 



The foundations of homology are a mixture in varying propor- 

 tions of comparative anatomy studied profoundly, of paleontolog- 

 ical data too often incomplete, and of a hypothetical phylogeny, 

 together with a dose, not to be overlooked, of that mysticism with 

 which natural philosophers constructed their archetype. 



This formula may appear a little irreverent to the devotees of 

 morphology; it is just, nevertheless. If we go to the bottom of 

 things, we must recognize this fact: to homologize is simply to 

 compare, to establish resemblances and differences in character- 

 istics, and to proclaim that these are casual, secondary, while those 

 are fundamental. 



Now, there is nothing more delicate than pronouncing upon the 

 comparative dignity of characteristics. There is a question of the 

 orientation of ideas, dependent upon time and place, a question of 

 mode of which it is prudent to be suspicious. 



When R. Owen distinguished in the determination of homologies 

 physiological characteristics from anatomical, and established the 

 difference between analogies and homologies, he rendered a real 

 service, for there is always an advantage in not confounding things 

 which are distinct; but it is less certain that he did a good thing 

 when he gave the precedence to homology over analogy in the com- 

 parison of characters, for it has led to an exaggerated disdain of 

 physiological characteristics. 



When we proclaim an homology like that of the lungs of mammals 

 with the swimming-bladder of fishes, for example, we assume a 

 grave and sententious tone, as if we were filled with a feeling of 

 our own merit in announcing a fundamental truth which remains 

 hidden in a superficial examination. If, on the contrary, we announce 

 an analogy, we take a tone light, and almost a little contemptuous, 

 in order to set off well the small value of a wholly superficial re- 

 semblance in which we must not place too much confidence. 



Is this right? 



