OTHER FACTORS OF EVOLUTION 123 



cat being less strictly carnivorous in its diet than any wild feline 

 species ; I have seen a French kitten eating vegetables as readily as 

 meat. According to Cuvier the intestines of the domesticated pig 

 exceed greatly in proportionate length those of the wild boar. 

 In the tame and wild rabbit the change is of an opposite nature, 

 and probably results from the nutritious food given to the tame 

 rabbit." 



Turning now to examples more recently made known I may say 

 that the transmission of acquired characters among Bacteria is 

 sometimes cited in this connection. Facts of this kind could be 

 multiplied to almost any extent,' but seeing that these organisms 

 possess no nucleus, and, for the most part, multiply merely by 

 fission, we have here only to do with ' discontinuous growth,' and 

 a process lying at the root of heredity rather than with heredity 

 itself. The very similar facts that have been made known by 

 Klebs, L. Errera and others as to the transmission of acquired 

 characters in lower Fungi are, however, more worthy of being 

 cited. One of the observations by Errera will be found recorded 

 by Spencer ; " while other important observations of the same kind 

 have been published by George Massee in a recently issued number 

 of the ' Philosophical Transactions' (197, B), showing that in the 

 course of from twelve to sixteen generations several ordinary 

 saprophytic Fungi could be made to take on a parasite habit, 

 and perpetuate themselves as parasites. 



Haeckel regards the spiral shape of the shells of Gasteropods as 

 " a very fine instance of the inheritance of acquired characters." 

 He says the snail's house "is in essence a spirally coiled tube, 

 closed at the upper end and open at the lower j(or mouth) : the 

 mollusc can at any moment withdraw into its tube. The compara- 

 tive anatomy and ontogeny of the snail teach us that this spiral cell 

 came originally from a simple discoid or cylindrical dorsal covering 

 of the once bilaterally-symmetrical mollusc, by the two sides of the 

 body having an unequal growth," 3 the particulars of which he then 

 traces. Haeckel likewise regards the asymmetrical shapes of flat- 

 fishes, such as soles, flounders, and turbots, as results of changes 

 that they have gradually acquired through many generations 

 owing to their habit of lying on one side (right or left) at the 



• Some good examples have recently been cited by Prof. Adami, of Montreal, 

 in the " Brit. Med. Jrnl.," May 29, 1905, p. 1135. 



2 " Biology," II, p. 623. 



3 " The Wonders of Life," p. 185. 



