DARWINISM AND EVOLUTION. 9 



That portion of the organism by which this adjustment is 

 wrought, consists in all cases of protoplasm. 



From the oxidation of this substance and from its concomitant 

 re-integration or restoration by the taking-in of new matter, result 

 the phenomena which we term vital. 



These phenomena are growth and reproduction ; and repro- 

 duction is a form of growth. 



1. More organisms perish than survive. 



It is hardly needful to insist upon this with respect to the 

 vegetable world, though Linnseus has calculated that if an annual 

 plant produced only two seeds (and there is no plant so unpro- 

 ductive as this ; they are often prodigiously prolific) and their 

 seedlings next year produced two, and so on ; then in 20 years 

 there would be a million plants. 



As regards animals, the elephant is reckoned the slowest 

 breeder of all. Assuming that it begins breeding when thirty 

 years of age, and goes on breeding till ninety years old, bringing 

 forth six young in the interval, and surviving till one hundred 

 years old ; then after a period of about 750 years there would 

 be nineteen million elephants alive, descended from the first 

 pair. 



Slow-breeding man has doubled in twenty-five years ; and at 

 this rate in less than a thousand years there would literally not 

 be standing-room for his progeny on the face of the earth. 



A viviparous fish, such as the Blenny, brings forth between 200 

 and 300 young every season, all alive and playing round the 

 parent together. 



Of the oviparous fish, the Herring will yield 10,000 eggs; the 

 Mackerel 500,000; the Flounder over 1,000,000; while the Cod 

 spawns annually 9,000,000 of eggs. 



It should be remarked, as explaining great differences of 

 fecundity, that they follow the law that, on the one hand, com- 

 plexity of organisation is hindered by reproductive activity, and 

 that, on the other hand, when a higher degree of organisation is 

 reached, reproduction goes on less vigorously. 



It is clear, however, that more organisms perish than survive. 

 2. It is equally clear that no two individuals are exactly alike. 

 On the contrary, the differences in the offspring of the same 

 parent are often well marked. 



Robert Dick, who was opposed to the Darwinian doctrine, 

 writing on wild roses, says, " Take the rosa spinosissima, or 

 " thorny rose ; how very unlike the common dog-rose, rosa 

 " canma, it is. Would you believe that one bush of it on the 

 " boulder clay here (Thurso) has put forth flowers hardly dis- 

 " tinguishable from dog-roses ; the leaves large, the flowers white, 

 "the prickles hooked, and so on. Some stocks of rosa 

 " spinosissima have pink petals; in dry years red petals and 



