474 NINETEENTH CENTURY. PT. ill. 



wide or impassable barrier from the home where first it 

 arose, and where climate, soil, and the other plants among 

 which it had to hold its own, were very different from those 

 now surrounding it. 



All these new interests are now within the grasp of the 

 student of botany, together with a host of observations 

 regarding internal plant-structure, and the nature and con- 

 tinuity of the germ-plasma in plants as lately propounded 

 by Professor Weissman. In fact, physiological botany has 

 become one of the most interesting and suggestive of 

 studies, while such men as Bornet, Muret, Schimper, de 

 Bary, and others, have now worked out the difficult question 

 of the fertilisation of ferns and mosses, in which, neverthe- 

 less, we trace the connection of their modes of fructification 

 with those of higher plants. 



When again we turn to Zoology we find still more the 

 healthy influence of a connected theory of life. For among 

 animals there is such an immense variety of forms that the 

 gradations of structure from the simplest to the highest, and 

 their relations to each other, are a source of never-failing 

 interest. Here the investigations of Parker, Balfour, and 

 others (see p. 440), come in to help us, by showing the 

 resemblance of the embryos of higher forms to the various 

 gradations found in lower ones of the same or of nearly 

 allied groups ; and structures which were formerly merely 

 puzzling anomalies now find their true place as links in 

 the tangled web and woof of gradually developing animal 

 life. So, too, when we see such different structures as the 

 fin of a fish, the wing of a bird, the leg of a horse, and the 

 arm and hand of a man, formed all on the same general 

 plan, we no longer fall back helplessly on the idea that 

 mere poverty of invention caused them to be created on 

 the same lines. We have now a sufficient reason for theii 



