156 THE CANADIAN NATURALIST. [Vol. vi. 



view has been abandoued that the complication of structure rises 

 in a continually increasing and continuous gradation from one 

 kingdom to the other, or extends in one line from one group to an- 

 other in either of the kingdoms separately. Evolution into a 

 gradually increasing complexity of structure and function no 

 doubt exists in both, so that types of formation must be acknow- 

 ledged to pervade, accompanied by typical resemblance of the plan 

 of formation of a most interesting nature ; but it has become more 

 and more apparent in the progress of morphological research that 

 the different groups form rather circles, which touch one another 

 at certain points of greatest resemblance, rather than one continu- 

 ous line, or even a number of lines, which partially pass each other. 

 Certain simpler bodies of the two kingdoms^of nature thus exhibit 

 the increasing resemblance to each other, until at last the differ- 

 ences between them wholly disappear, and we reach a point of 

 contact at which the properties become almost indistinguishable, 

 as in the remarkable Protista of Haeckel and others. I fully 

 agree, however, with the view stated by Professor Wyville Thom- 

 son in his introductory lecture, that it is not necessary on this 

 account to recognize with Haeckel a third intermediate kingdom 

 of nature. Each kingdom presents, as it were, a radiating expan- 

 sion into groups for itself, so that the relations of the two king- 

 doms might be represented by the divergence of lines spreading in 

 two different directions from a common point. Recent observa- 

 tions on the chorda dorsalis of some Ascidians (or supposed no- 

 tochord) tend to revive the discussion at one time prevalent, but 

 long in abeyance, as to the possibility of tracing a homology be- 

 tween the vertebrate and invertebrate animals ; and, should this 

 correspondence be confirmed and extended, it may be expected to 

 modify greatly our present views of zoological affinities and classi- 

 fication, and be an additional proof of the importance of minute 

 and embryological research in such determinations. The recog- 

 nition of homological resemblance of animals, to which in this 

 country the researches of Owen and Huxley have contributed so 

 largely, form one of the most interesting subjects of contemplation 

 in the study of comparative anatomy and zoology in our time ; 

 but I must refrain from touching on so seductive and difficult a 

 subject. 



NATURAL SCIENCE IN SCHOOLS. 



There is another topic to which I can refer with pleasure as 

 connected with the cultivation of biological knowledge in this 



