I] CHEMICAL EMBRYOLOGY 17 



an explanation of life, cannot lead to any conclusion unless that 

 fundamental characteristic common to all vital phenomena of pre- 

 senting a purposive, teleological, or finaUstic aspect in their most 

 typical manifestations is first thoroughly examined." The most suc- 

 cinct account of his views and of the exact biologist's answer to them will 

 be found in his Man Not a Machine, and in the volume Man a Machine 

 in the same series. The way in which they affect embryology is 

 significant, and may be found in his chapter called "Finalism of the 

 generative and regenerative phenomena". "Even if", he says, "the 

 organism could be explained as a physico-chemical machine, there 

 would still remain to be explained the most fundamental thing — how 

 the machine constructed itself The purposiveness of the ontogenetic 

 development is too evident to be denied. It results from the con- 

 vergence of manifold morphogenetic activities to one sole end, that 

 is, to the formation of a marvellous functional unity, every part of 

 which serves to maintain the life and guarantee the well-being of the 

 whole. The embryo in its development manifests at every stage a 

 ' harmony of composition ' as Driesch calls it, which has a touch of 

 the marvellous ; parts and elements of an organ develop independently, 

 but when they have finished their development they are found to 

 fit together perfectly like the parts of a machine and the one so 

 answers to the other that they unitedly form one complex organ. 

 Thus the mouth and intestine of the sea-urchin begin their develop- 

 ment at two points distant from each other and develop indepen- 

 dently, but as they grow the one moves towards the other, so that 

 when development is ended they fit together perfectly and form a 

 single canal." This passage illustrates the line of argument found 

 throughout Rignano, and I will not remark on it further than to 

 draw attention to the mention of the marvellous in it, another hint, 

 if any were needed, of that strain of misplaced "numinous instinct" 

 which seems to be present in all biological vitaHsts. Omnia exeunt 

 in mysterium would seem to be "a discouraging maxim" for the 

 scientific worker. "The direction", Rignano goes on to say, "of 

 ontogenetic development toward a predetermined end is also in- 

 fluenced by the fact that the embryo overcomes early disturbances 

 which might deflect it from its course. Ontogenesis thus seems to be 

 marshalled by some occult intelligence or entelechy in the same way 

 that the construction of a machine and the direction of its work is 

 presided over by the mind of the engineer." 



