2.62. THE HISTORY OF BIOLOGY 



tion of the blood and bullet-wounds he propounds a curious theory of the 

 blood as a vital principle, which he further developed in a number of lectures 

 on the musculature. He considers the blood to be a kind of primary matter 

 in the body, whence every other bodily substance is derived; all living matter 

 is of a similar nature, so that even the blood of one animal can be transferred 

 into another of a different genus (modern investigations show this to be an 

 error), and life is a kind of independent principle in the body which prevents 

 it from dissolving — a theory reminiscent of Stahl. Though Hunter pro- 

 duced a few solitary brilliant ideas, yet from a theoretical point of view he 

 did not contribute very much to the development of biology; his genius for 

 comparative anatomy was, however, probably greater than anyone else's in 

 his time, and in many respects it has borne fruit in more recent times. 



Peter Simon Pallas was born in Berlin in the year 1741, the son of a 

 doctor, and studied medicine in his native country, at Gottingen, and at 

 Leyden. At the latter university he got his degree with an essay on intestinal 

 worms. He afterwards spent some years in Holland, working at zoological 

 collections from the tropics, which he described in a series of papers. In 

 1768 he was summoned by the Russian Government to take part in an im- 

 portant expedition which was being sent to Siberia to explore that country 

 from the point of view of natural history and economics. Pallas spent six 

 years travelling in Siberia, reaching as far as Amur, and he brought home an 

 immense quantity of scientific material, which he worked at in St. Peters- 

 burg for a number of years. In 1793 he was sent to explore the Crimean 

 district, which had just then become part of Russia, and he stayed there for 

 a long time, living on an estate which the Empress Catherine II gave him. 

 Finally, however, he moved back to Berlin in order to be in closer touch 

 with the scientific world, and there he died in 1811. 



Pallas' s ivork on intestinal worms and on mammals 

 Pallas's contribution to the development of biology is particularly many- 

 sided. In his doctor's dissertation he incorporated all the observations he 

 was able to obtain dealing with intestinal worms and he sought to prove 

 that they enter the human body from outside — in his time it was univer- 

 sally assumed that they arose out of "tainted fluids" in the body. In a work 

 on the zoophytes he tries to find out the classification of these animals, 

 their conditions of life, and their relation to animals and plants. He endeav- 

 ours to prove that the zoophytes form a true transition between animals and 

 plants, following the ancient saying that nature never makes any jumps. 

 He also made a number of interesting observations, both anatomical and 

 biological, on worms and expressly points out how utterly heterogeneous 

 the Linnasan class bearing this name is. Primarily, however, Pallas is a 

 student of vertebrates. In his Spicilegia zpologica in particular — a collection 

 of monographs, issued in separate numbers — he describes in detail a number 



