244 



SCIENCE. 



[N. S. Vol. VIII. No. 191. 



The establishment of the epigenetic view is 

 largely due to exact investigation and 

 modern methods of research, but more 

 especially to the results of modern embry- 

 ology and to the fairly well digested facts 

 we now have relating to the development 

 of one or more tj'pes of each class of the 

 animal kingdom. 



To use a current phrase, the evolution 

 theory as now held has come to stay. It is 

 the one indispensable instrument on which 

 the biologist must rely in doing his work. 



caterpillar, at first scarcely as large as a bit of thread, 

 contains its own teguments threefold and even eight- 

 fold in number, besides the case of a chrysalis, and a 

 complete butterfly, all lying one inside the other.' 

 This view, however, we find is not original with 

 Lacordaire, but was borrowed from Kirby and Spence 

 without acknowledgment. These authors, in their 

 Introduction to Entomology (1828), combated 

 Herold's views and stoutly maintained the old 

 opinions of Swammerdam. They based their opin- 

 ions on the fact, then known, that certain parts of 

 the imago occur in the caterpillar. On the other 

 hand, Herold denied that the successive skins of the 

 pupa and imago existed as germs, holding that they 

 are formed successively from the ' reie mucosum,' 

 which we suppose to be the hypodermis of later au- 

 thors. In a slight degree the Swammerdam, Kirby 

 and Spence doctrine was correct, as the imago does 

 arise from germs, i. e., the imaginal disks of Weis- 

 manu, while this was not discovered by Herold, 

 though they do at the outset arise from the hypoder- 

 mis, his rete mucosum. Thus there was a grain of 

 truth in the Swammerdam, Kirby and Spence doc- 

 trine, and also a mixture of truth and error in the 

 opinions of Herold. 



The discovery by Weismann of the imaginal discs 

 or buds of the imago in the maggot of the fly, and 

 his theory of histolysis, or of the more or less com- 

 plete destruction of the larval organs by a gradual 

 process, and his observation of the process of building 

 up of the body of the imago from the previously 

 latent larval buds, was one of the triumphs of mod- 

 ern biology. It is, therefore, not a little strange to 

 see him at the present day advocating a return 

 to the preformation views of the last century 

 in the matter of heredity. Of course, it goes 

 without saying, as has always been recognized, that 

 there is something in the constitution of one egg 

 ■which predestines its becoming an insect, and in that 

 of another which destines it to produce a chick. 



It is now almost an axiomatic truth that 

 evolution is the leaven which has leavened 

 the whole lump of human intellectual ac- 

 tivity. It is not too much to claim that 

 evolutionary views, the study of origins, of 

 the beginning of organic life, the genesis of 

 mental phenomena, of social institutions, of 

 the cultural stages of different peoples and 

 of their art, philosophy and religion — that 

 this method of natural science has trans- 

 formed and illuminated the philosophy of 

 the present half-century.* 



It is naturally a matter of satisfaction 

 and pride to us as zoologists that, though 

 evolution has been in the air from the days 

 of the Greek philosophers down to the time 

 of Lamarck, the modern views as to the 

 origin of variations, of adaptation, of the 

 struggle for existence, of competition, and 

 the preservation of favored organs or species 

 by selection, are the products of single- 

 minded zoologists like Darwin, "Wallace, 

 Fritz Miiller, Semper and Haeckel. It is 



* It is worthy of mention that just fifty years ago 

 in his ' Future of Science,' written in 1848, at the age 

 of 25, Eenan, who perhaps first among philosophers 

 and students of comparative philology adopted the 

 scientific method, i. e., the patient investigation of as 

 wide a range of facts as possible, wrote : "I am con- 

 vinced that there is a science of the origins of man- 

 kind and that it will be constructed one day, not by 

 abstract speculation, but by scientific researches. 

 What human life in the actual condition of science 

 would sufBce to explore all the sides of this single 

 problem ? And still, how can it be resolved without 

 the scientific study of the positive data? And if it 

 be not resolved how can we say that we know man 

 and mankind ? He who would contribute to the so- 

 lution of this problem, even by a very imperfect es- 

 say, would do more for philosophy than by half a 

 century of metaphysical meditation " (p. 150). Again 

 he says : "The great progress of modern thought has 

 been the substitution of the category of evolution for 

 the category of the ' being ; ' of the conception of the 

 relative for the conception of the absolute, of move- 

 ment for immobility. Formerly everything was con- 

 sidered as 'being' (an accomplished fact) ; people 

 spoke of law, of religion, of politics, of poetry in an 

 absolute fashion. At present everything is considered 

 as in the process of formation " (p. 169). 



