CATALYSIS AS THE EFFICIENT CAUSE OF EVOLUTION 249 



understanding, and gradually advance under the training of social 

 institutions." 



The great poet Johann Wolfgang von Goethe (1749-1832) was 

 much interested in science, and observed, among other things, 

 that the flower consists of metamorphosed leaves. In fact the term 

 morphology was introduced by Goethe in 1817, and this branch 

 of science has had much to do with the development of evolu- 

 tionary theory. 5 



The foundations of comparative embryology were laid by 

 Karl E. von Baer (1792-1876), who discovered the human ovum. 

 His Biogenetic Law may be summarized (following Singer) as 

 follows: 



(1) In development, general characters appear before special 

 ones. 



(2) Less general characters developed from more general ones; 

 then follow the special characters. 



(3) As development proceeds, animals of one species diverge 

 continuously from animals of another species. 



(4) In the course of development, a higher animal passes 

 through stages which resemble stages in development of 

 lower animals. 



His law of "corresponding stages," in the development of ver- 

 tebrate embryos is exemplified by the story told of him that, when 

 he had forgotten to label some jars containing specimens preserved 

 in alcohol, he said: "I am quite unable to say to what class they 

 belong. They may be lizards, or small birds, or very young mam- 

 malia, so complete is the similarity in mode of the formation of the 

 head and trunk in these animals. The extremities are still absent, 

 but even if they had existed in the earliest stage of development 

 we should learn nothing, because all arise from the same funda- 

 mental form." Von Baer asked: 6 "Are not all animals in the 

 beginning of their development essentially alike, and is there not 

 a primary form common to all?" 



Developments in the newer sciences of morphology, embryology 

 and paleontology were steadily undermining the notion, acceptable 

 to ecclesiastics and accepted by authoritative scientists, that species 

 are fixed. Robert Chambers, a Scotch publisher, wrote (1843- 

 1846) what became a very popular book entitled "Vestiges of the 

 Natural History of Creation," which was published anonymously 

 because he did not want to bring on his publishing firm the 

 opprobrious charge of heterodoxy. In the course of his exposi- 



