404 HISTORY OF SCIENCE. 



different places, was nominated to the professorship of anatomy at the 

 University of Gottingen, then newly established, and where special care 

 was taken to secure the services of the best qualified persons for the 

 several academical chairs. Haller remained at Gottingen for some 

 time, but was afterwards obliged to resign his appointments from want 

 of health, and return to his native country. For a period of half a 

 century he continued from time to time to publish scientific disserta- 

 tions and treatises to the number of nearly two hundred. 



Haller was the first person who proved that in muscular tissue there 

 resides the special property of contracting under the influence of certain 

 stimuli. The movement of contraction is very rapid and marked, and 

 is accompanied by a swelling and wrinkling of the fibres of the muscle. 

 Haller affirmed that a necessary condition of this property, which he 

 termed irritability, was the distribution to the muscle of some nervous 

 power. The latter was, however, distinct from the proper irritability 

 of the muscular fibres which existed in themselves, although the dis- 

 tribution of nervous power was necessary for its exercise. In the 

 nerves Haller conceived sensibility was present, but not irritability. 

 Thus, to muscular tissue belongs irritability ; to nervous tissue, sensi- 

 bility : these were the special and peculiar functions of each tissue. 

 He denied that the irritability could be derived from the nerves, be- 

 cause although it was obvious that some action of the nerve may 

 stimulate the muscle, the motion produced cannot be derived from 

 the nerves, for it is impossible to suppose that they could impart to 

 other things that which they do not themselves possess. Haller also 

 proved that there are certain tissues of the body devoid of either sen- 

 sibility or irritability. But irritability, while residing in every part of 

 the body that is possessed of muscular fibre, is present in different 

 degrees and intensities in the various parts. It is most observable in 

 the heart, and more in the left ventricle than in the right. Next in 

 order come the intestines, the diaphragm, the voluntary muscles. From 

 repeated experiments Haller concluded that the heart and other in- 

 voluntary muscles are not excited to contract by a stimulation derived 

 from the nerves which are supplied to them from other parts of the 

 system, but they require their own special stimuli ; for example, it is 

 the blood within the ventricle which is the stimulus to its contraction. 

 Haller, indeed, reduced all the vital functions to these two sensibility 

 and irritability; the one seated in muscular, the other in nervous 

 tissues. This doctrine was strongly opposed by some physiologists of 

 the time. It was seen that those parts of the body which possessed 

 neither of Haller's two essentially vital properties were not the less 

 alive. Other physiologists defended the new doctrines, and from the 

 discussions which ensued materials for more accurate views were ob- 

 tained, as criticism detected errors or experiment ascertained facts. 

 It was shown that Halier had failed to recognize the excitability of 

 tissues other than the muscular and the nervous simply because he 



