1 42. THE HISTORY OF BIOLOGY 



farther north we go. During the sixteenth century the natural philosophers 

 were still mostly university teachers; such had been both Vesalius and Gali- 

 leo. In the seventeenth century, on the other hand, and still more so in the 

 eighteenth century, the universities cease to be the centres of scientific prog- 

 ress and become instead the seats of unproductive conservatism, mechanically 

 repeating the formulas inherited from the Middle Ages; the real pioneer 

 scientists are now private scholars. Descartes, Spinoza, Leibniz, as well as 

 Harvey and van Helmont, all worked, as we have seen, independently of the 

 universities, as we shall also find did several of the leading scientists among 

 their successors, in both the seventeenth and the eighteenth centuries. A new 

 type of bond of association between men of learning came to be established 

 in connexion therewith — namely, the scientific societies. Such "academies" 

 were founded during the seventeenth century all over Europe, earliest in 

 Italy, afterwards in all countries north of the Alps. Princes and distinguished 

 people allowed themselves to be nominated as patrons or to be elected honor- 

 ary members, thereby acquiring an interest in the study of nature. To pro- 

 mote this study they established laboratories and made collections of natural 

 objects — so-called "curiosity cabinets" — ■ mostly, it is true, as the name 

 implies, for their own amusement, but still in many cases for the benefit of 

 science, owing to the possibilities they offered for research and the grants 

 of money made by scientists in connexion therwith. All this naturally in- 

 creased, as it were, the social reputation of science and in this respect offered 

 a decided contrast to the Renaissance; whereas then the students of nature 

 had to live in inferior positions, during the seventeenth and eighteenth 

 centuries many of them held important posts in the community. The period 

 now to be described was thus in all respects a brilliant one for natural 

 science — a period which has no counterpart until we come to the latter 

 half of the nineteenth century. 



Discovery of the lymphatic system 

 As Harvey's immediate successors it is fair to regard those scientists who, 

 like him, studied the vascular system in man and the higher animals and thus 

 continued along the path he initiated. Mention has already been made 

 (Part I, p. 113) of hov/, even during Harvey's lifetime, a hitherto unknown 

 type of vessel was discovered — namely, the lymphatic duct system — and 

 how Harvey adopted an attitude of complete ignorance on the subject and 

 adhered to the ancient tradition. As a matter of fact, a year before the publi- 

 cation of Harvey's treatise on the circulation of the blood there appeared a 

 work on "the lacteal veins — a new discovery." — The author, who had 

 died the previous year, was an Italian physician named Gasparo Aselu 

 (1581-162.6). He had begun his profession as an army surgeon and afterwards 

 became for a time professor of anatomy at Pavia, but finally practised in 

 Milan. There he once carried out, together with some of his colleagues, a 



