1442 LIFE : OUTLINES OF GENERAL BIOLOGY 



time began to alter the whole aspect of the long embryonic science 

 of living things. It was not merely that a new world of minute 

 organisms was revealed; it was not merely that what had seemed 

 macroscopically simple was shown to be microscopically intricate; 

 the far-reaching advance was rather that many vital phenomena 

 became in a new way intelligible. Visible processes which had 

 seemed almost magical in their occurrence were made intelligible in 

 terms of the previously invisible. Thus although Harvey had 

 demonstrated the passage of the blood from the arteries to the veins, 

 he had not actually seen that passage, since it is effected by the 

 invisible network of capillaries. This, so well observed in the web 

 of a frog's foot, was demonstrated in the frog's lung by Malpighi 

 (1628-1694), born in the year of the publication of Harvey's great 

 book. Similarly an insect's life is quite unintelligible until the air- 

 tubes or tracheae are recognised as such; and though the larger ones 

 are readily seen with the unaided eye in a big beetle, this is not 

 possible in smaller types; and in any case the significant fact is the 

 intricate system of previously invisible branching tubes by which 

 air is carried to every hole and corner of the body. Here the historian 

 would also recall the work of Swammerdam (1637-80). It 

 gradually became possible to discover the young stages of organisms, 

 including the mysteriously intruded parasites; and here great 

 honour is due to the memory of Leeuwenhoek (1632-1723), who 

 discovered not merely Infusorians, but Bacteria, and sperm-cells. 

 With this brief introduction we must now abandon all attempt at 

 narrative, and be content with an enumeration of what may be 

 regarded as some of the most important of the great events in the 

 subsequent history of biology. 



Linnaeus (1707-78) included Plants and Animals under the 

 common title Organisata, and laid the foundations of Taxonomy. 



Cuvier (1769-1832) laid emphasis on the correlation of organs in 

 the body, and laid the foundations of Comparative Anatomy, in 

 which, for the first time, he began to do justice to fossils. 



Of far-reaching influence was the idea of unit}'' of plan underlying 

 great series of organic structures — the idea of homologies which was 

 for a time dominant in Goethe's versatile mind. For he was one of 

 the first to have a vivid realisation of the higher plant as an axis 

 with leafy outgrowths, protean in their "metamorphosis" into all 

 manner of varied leaf-forms, and even into all parts of the flower — 

 sepals and petals, stamens and carpels alike. He made his partial 

 mistakes, no doubt, as with his interpretation of the mammalian 

 skull as equivalent to a series of vertebras, but he had a vivid 

 interpretative insight into unity of structure. To Goethe the term 

 "morphology" is due— -in itself a great contribution to science, and 

 he is also to be remembered and studied as a philosophico-poetical 

 evolutionist — right in idea, even when his facts were wrong. 



