4 LIFE : OUTLINES OF GENERAL BIOLOGY 



logical anatomists of surpassing skill, as from Reaumur and Lyonet 

 to Lacaze-Duthiers and Dclage. But the acheivements of hand- 

 controlled dissecting needles are now far surpassed by the micro- 

 scopic manipulations which enable Robert Chambers, and his 

 students too, to excise the nucleus from an amoeba, and even dissect 

 it! This inquiry into the static aspect of organisms — their structure 

 in general and in detail — leads to a recognition of their character- 

 istic architectural plans and styles, and even discloses their engi- 

 neering principles of construction. Moreover, it leads us to perceive, 

 through comparative anatomy, certain deep-seated structural 

 resemblances or "homologies" by help of which our old popular and 

 "Natural History" classifications — e.g. of all sorts of marine 

 creatures as "fish" — have long been in process of replacement by 

 more rationally architectural ones. Thus comparative morphology 

 affords the basis for classification proper, commonly called Tax- 

 onomy. This, in fact, is the subject of Linnreus's fundamental Opus 

 — his Systema Natures — from the tenth edition of which (1758) 

 systematic botanists and zoologists have long been agreed to date 

 the opening of their era. For though the Drama Naturoe, scene by 

 scene, has its spectator and recorder in the ecologist, it is the service 

 of the taxonomist to enumerate and arrange the Dramatis Personae, 

 as for the comparative anatomist to supervise it. Hence an impor- 

 tant though brief section of this book deals with the principles and 

 results of the inquiries into organic architecture and orderly 

 arrangement. 



DEVELOPMENTAL.— The study of adult structure, from Aris- 

 totle to the anatomist of to-day, naturally leads to inquiry into 

 earlier stages; and thence back to the embryo and to the egg. 

 Thus arose the description of the individual Becoming or genesis: 

 descriptions of the developing chick within its shell, the bee-grub 

 in its waxen chamber, the embryo skate within the "mermaid's 

 purse", and the tadpole forming within its sphere of spawn-jelly. 

 How arises the individual organism — plant as well as animal, as a 

 whole and in each of its parts? The answer to this question — to 

 which a corresponding physiological one has to be added — is 

 Embryology. 



But this developmental question cannot be restricted to eggs 

 and embryos; it must be extended to larval and adolescent stages; 

 it must be continued throughout the whole biography up to adult 

 form and life. There even arises a still wider conception of this sub- 

 science, as including not only progressive changes, but retrogressive 

 as well. These retrogressions or involutions may begin very early, 

 and also reappear with age, in the waning of strength in normal 

 senescence, and, in a few cases among animals, but often in man- 

 kind, beyond this into disintegrative senility. Hence the life of the 



