APPENDIX 427 



reason that such an indivisible organic unit does not exist : 

 it does not exist because all single forms are directly or in- 

 directly connected with one another. 



Herewith I come to the consideration of the second part 



of my subject. 



II 



The doctrine of evolution, we all know, assumes that the 

 whole of nature forms a great whole in particular, that the 

 animal kingdom is a connected whole. It is very remarkable 

 that the knowledge of the grounds on which this doctrine 

 rests has not become so widely extended among us in 

 Germany as might have been expected. I believe the reason 

 of this lies in the circumstance that German research has 

 almost entirely confined itself to the investigation of anatomy 

 and embryology ; while Darwin, who infused a new life into 

 the doctrine of the evolution of species, took account chiefly 

 of the external forms of animals and plants, and particularly 

 of their biological relations. It is for the greater number 

 of men absolutely impossible to follow the researches into 

 details on which the doctrine of evolution among us, in the 

 German way of treating it, is supported. The study of 

 systematic zoology and botany, which principally depends on 

 the investigation of external form, has even been expressly 

 and publicly tabooed by the principal representatives of 

 Darwinism, and it has been declared scientifically unallow- 

 able to occupy one's self with such things at all. I have long 

 been of a different opinion, and believed it would be profit- 

 able to fix the attention keenly for once on a living creature 

 commonly accessible, to consider the external relations of 

 some single animal or some single plant, and in this way to 

 seek material for the discussion of the connection of forms 

 with one another. And, in fact, I obtained in this way some 

 very remarkable results. 



Hitherto the significance of the markings, the spots and 



