30 THE BIOLOGY OF THE SEASONS 



watching many of these young things is that there is much 

 truth in the frequently exaggerated idea of recapitulation. 

 The conclusion that an animal climbs up its own genealogical 

 tree is not to be taken literally, and Haeckel's more stately 

 way of phrasing the idea, " Ontogeny tends to recapitulate 

 Phylogeny," requires numerous reservations. The living 

 creature is specific, itself and nothing else, from the very 

 start, and it may show this in unexpected ways and very 

 early in development ; but yet its early form and structure 

 may in many cases be accurately described as old-fashioned 

 and generalised. It is not till the sixth day that the chick 

 within the egg begins to put on distinctively avian features, 

 and it seems to us not inaccurate to say that during the 

 previous five days it has been following a path precisely 

 parallel to that along which a young crocodile travels. 

 In a great number of cases, it is true, the young creature 

 is a sort of nurse or vehicle of the definitive organism that 

 is to be, and its salient features are adaptive to peculiarities 

 of the larval life and not in the very least ancestral ; at 

 the same time, when we inquire into the details of the 

 organ-making (organogenesis) we often find that the 

 successive developmental stages bear a striking correspond- 

 ence to what we believe were the successive evolutionary 

 steps. For these and other reasons based on animal and 

 human child-study we adhere to a modified form of the 

 much-abused recapitulation-doctrine, believing that the in- 

 dividual development of an organism tends to be a general 

 recapitulation, often much condensed and telescoped, of the 

 historical evolution of its race. 



When we observe the growing of young things, whether 

 they be seedlings or tadpoles, we have to reconcile two 

 sets of facts organic inertia on the one hand and organic 

 divergence on the other. On the one hand, we see the 

 persistent tendency to complete hereditary resemblance, 



