8o6 POPULAR SCIENCE MONTHLY. 



THE EVOLUTION- OF COLONIES. 



By JAMES COLLIER. 

 IV.— THE LAW. 



IT is the great unquestioned addition to Darwinism made by 

 Haeckel that the history of the embryo is shown to recapitulate 

 the history of its ancestral species. As stated by Haeckel's author- 

 ized expositor, Mr. Lester Ward, the law has a fascinating simplicity. 

 The develoj)ment of successive species being the mechanical cause of 

 the development of the embryo, every transmutation undergone by the 

 former in the course of ages is passed through by the latter. From 

 the primary cell onward, the successive species are faithfully repro- 

 duced by successive stages in the growth of the embryo. Man is 

 thus first of all an amoeba, he advances to the humble condition of a 

 worm, is transformed into a lamprey, grows into a kind of fish, is for- 

 tunately only a bit of a reptile, is promoted to be a marsupial, a lemur, 

 an ape, a man-ape, before he emerges in distinctly human form. 

 So far, Haeckel. Other naturalists find the parallel more complex. 

 In no case, according to Prof. Henry Drummond, is the recapitula- 

 tion of the past complete. " Ancestral stages are constantly omitted, 

 over-accentuated, condensed, distorted, or confused; while new and 

 undecipherable characters occasionally appear." Haeckel has no dif- 

 ficulty in accounting for these new and undecipherable characters. 

 They are the priceless records of formerly existing but now extinct 

 species. By their aid we can recover the vanished past. It was a 

 wonderful feat when Kant predicted, from certain disturbances in the 

 planetary orbits, that the planet Neptune would one day be dis- 

 covered. It was a great thing when Owen was (rightly or wrongly) 

 believed to have reconstructed the moa from a thigh bone, or when 

 from a few small molar teeth found in Germany and l^orth America 

 two lost species were built up. Haeckel has shown a still more daring 

 exercise of the scientific imagination in confidently assuming the ex- 

 istence of species of which no trace has ever been found. Of the 

 twenty-one species between the moner and man nearly one half are 

 hypothetical. ISTot even their fossil remains have been discovered. 

 But the German idealist betrays no doubt of their reality. That they 

 are vouched for by answering stages in the growth of the embryo is 

 evidence enough. In at least one case later research seems to have 

 vindicated his prevision. 



The analogy is strictly limited to species in the line of descent. 

 No creature is the inheritor of the whole pre-existent organic crea- 

 tion. Man himself, the crown of Nature and its lord, is heir to only 

 three of the seven animal subkingdoms. Never having been a 



