MODERN BIOLOGY 357 



lated into German. As regards the system, Meckel to a certain extent adopts 

 an attitude of indecision; on the one hand he has to accept Cuvier's types, 

 but on the other the whole object is to prove the possibility of one single 

 primal type; consequently Meckel rejects the definite line that both Cuvier 

 and Lamarck draw between vetebrates and invertebrates, and as an inter- 

 mediary form between them he places the ink-fish, whose carapace is declared 

 to be the rudiment of a backbone. Further, Meckel, like Lamarck, believes 

 in a common spontaneous generation whereby a number of lower life-forms 

 arise in various parts of the world and thus increase the number of existing 

 species. In this, as in his general idea of the origin of life-forms, Meckel in- 

 clines towards Lamarck, his indebtedness to whom he acknowledges when 

 quoting him. Each of them sought to produce a "history of natural creation," 

 and it must be admitted that on this subject Meckel was able to derive ad- 

 vantage both from the work of his predecessors and from his own thorough 

 knowledge of anatomy. Meckel's theory of origin thus contains many in- 

 teresting and suggestive ideas of importance for the future of science, but 

 it certainly contains also masses of weird fancies and ridiculous conclusions. 

 What distinguishes Meckel's theory from Lamarck's — and even from Dar- 

 win's — is the fact that he does not assume one single cause of evolution, but 

 a number of causes, and his exposition herein lacks the easy comprehensibil- 

 ity that characterizes both his predecessor's and his successor's work, which, 

 indeed, explains why it is that he failed to win the same degree of popu- 

 larity that they did. Among the causes of evolution, it is true, Meckel, like 

 Lamarck, lays great stress on the influence of habit and environment, or, as 

 he expresses it, the formative influence of mechanical forces. In this connexion 

 he quotes stories of how bobtailed equine and canine races have been created 

 as a result of the tails of the animals' ancestors having been docked, and in 

 the same way mechanical pressure in the course of ages has produced the 

 numerous interlacings and various divisions of the digestive canal, as also 

 other changes in the internal organs. And he ascribes similar transforming 

 force to light, heat, and electricity; in particular, the electrolysis of fluids, 

 which was then newly discovered, leads him to indulge in fantastic specu- 

 lations upon the effect of this force on the development of life-forms. More- 

 over, he drags into his theory of the formation of species the entire category 

 of mostly unknown phenomena that give rise to malformations; thus, he 

 cites the old belief that mothers can give birth to malformed children after 

 "getting a fright," as at least a plausible cause of the appearance of new life- 

 forms, and he finally mentions hybridization as an important cause of the 

 arising of fresh species. To this factor in the evolution of life, however, 

 which, as is well known, has excited special attention in modern times, he 

 attributes utterly irrational eff^ects: he believes in old tales of a cross between 

 a cat and a hare, a cock and a duck. There is indeed far better justification 



