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were ample, and lie studied just to please himself. During his school 

 holidays, as he lived near the sea, he studied the murex, that yields 

 the Tyrian purple, the process of reproduction of lost limbs in crabs, 

 the movements of star fishes, phosphorescence (1708-1715). Already 

 his scientific bias declared itself. He in later life made important 

 contributions to the problem of the manufacture of steel and tin- 

 plating, to the making of porcelain (1735), and devoted much attention 

 to forestry. His observations on the silk of spiders were made in 

 1714. The thermometer which bears his name was invented in 1731. 

 His other great works were Insects, in 1737-48 (12 vols.) ; Incuba- 

 tion of the Chick, and, what concerns us most, Sur la Digestion 

 des Oiseaux (Digestion of Birds), Mem. des Acad, des Sc, Paris 1752, 

 p. 266, though the work was begun in 1749. He was killed by a fall 

 from his horse in 1757. 



He made use of a fact in comparative anatomy, viz., that certain 

 birds regurgitate the indigestible parts of their food. He gave to a 

 tame kite metal tubes — containing flesh, starch, bone, or other 

 substance — and provided with a grating of threads at both ends to 

 prevent the escape of the contents. He found that the contents of the 

 regurgitated tubes were in part dissolved, and what remained showed 

 no sign of putrefaction. Filling such tubes with sponge, he was able 

 to obtain a small quantity of gastric juice — which he found turned 

 blue paper red. This juice he used to try what we now know as 

 artifical digestion in vitro, and found that meat was partially dissolved 

 thereby and that there was no putrefaction. It was evident, then, that 

 gastric digestion was not due to trituration of the food, that it was 

 not a putrefactive process, but that the gastric juice had a solvent 

 and, indeed, anti-putrefactive power. It was not until Spallanzani 

 took up the subject again, that this subject was carefully 

 investigated. 



ALBRECHT VON HALLER. 



1708-1777. 



I HAVE purposely passed over the views of Boerhaave on physio- 

 logical problems. He held a sort of even balance between the 



iatro -mechanical and iatro-chemical schools. It was his Institu- 

 tiones Medicce which' secured him one of his' most brilliant pupils, of 

 whom we shall speak next. Indirectly, therefore, the MSS. of Vossius, 

 the kindly advice of a burgomaster, and a dispute about Spinoza 

 led Boerhaave to medicine, and the latter's " Institutions " led Haller 

 to Leyden. 



It was a matter of great importance to the development of 

 physiology that the fame and works of Boerhaave attracted to 



