TRANSACTIONS OF THE SECTIONS. 95 



connected phenomena; but, aided by a philoaophic metlicd, the observed facta 

 become scientific propositions, what was apparently insignificant becomes full of 

 meaning, and we get glimpses of the consummate laws which govern the whole. 



I shall leave the consideration of Biology in its purely physiological aspect to 

 the President of the Physiological Subsection, and shall here confine myself to 

 those departments which are more or less controlled by morphological laws. 



Importance of Anatomy. 



The first step in our morphological study of living beings is to obtain an 

 accurate and aclequate knowledge of the forms of the individual objects which 

 present themselves to lis in our contemplation of the animal and vegetable 

 kingdoms. For such knowledge, however, much more is needed than an acquaint- 

 ance with their external figure. We must subject them to a searching scrutiny; 

 we must make ourselves familiar with their anatomy, which involves not only a 

 knowledge of the forms and disposition of their organs, internal as well as external, 

 but of their liistology or the microscopic structm-e of the tissues of which these 

 organs are composed. Histology is nothing more than anatomy carried to its 

 extreme term, to that point where it meets with the morphological unit, the ulti- 

 mate element of form, and the simplest combinations of this out of which all the 

 organs in the living body are built up. 



Among the higher animals Anatomy, in the ordinary sense of the word, is 

 suificiently distinct from Histology to admit of separate study ; but in the lower 

 animals and in plants the two become confounded at so many points as to render 

 their separate study often impracticable. 



Now the gi-eat prominence given to Anatomy is one of the points which most 

 eminently distinguish the modern schools of Biology. 



Development, 

 Another order of morphological facts of no less importance than those ob- 

 tained from anatomical study is derived from that of the changes of form which 

 the individual experiences during the coiu'se of its life. We know that every 

 organized being commences existence as a simple sphere of protoplasm, and that 

 from this condition of extreme generalization all but the very lowest pass through 

 phases of higher and higher specialization, acquiring new parts and differentiating 

 new tissues. The sum of these changes constitute the development of the 

 organism ; and no series of facts is more full of significance in their bearing on 

 biological science than that which is derived from the philosophic study of 

 Development. 



Classification an H.ipression of Affinities. 



Hitherto we have been considering the individual organism without any direct 

 reference to others ; but the requirements of the biological method can be 

 satisfied only by a comparison of the various organisms one with the other. Now 

 the grounds of such comparison may be various ; but what we are at present con- 

 cerned with will be found in anatomical sti-ucture and in developmental changes ; 

 and in each of these directions facts of the highest order and of great significance 

 become apparent. 



By a carefully instituted comparison of one organism with another, we discover 

 the resemblances as well .as the difl'erences between them. If these resemblances be 

 strong and occur in important points of structure or development, we assert that 

 there is an affinity between the compared organisms, and we assume that the 

 closeness of the affinity varies directly with the closeness of the resemblance. 



It is on the determination of these affinities that all philosophic classification 

 of animals and plants must be based. A philosophic classification of organized 

 beings aims at being a succinct statement of the affinities between the objects so 

 classified, these affinities being at the same time so set forth as to have their 

 various degrees of closeness and remoteness indicated in the classification. 



Affinities have long been recognized as the giounds of a natural biological 

 classification; but it is only quite lately that a new significance has been given to 

 them by the assumption that they may indicate something more than simple 



