526 ANNUAL EEPORT SMITHSONIAN INSTITUTION, 1915. 



sometimes caused an increase in the strength of the beats in addition 

 to the quickening which had been ah'eady described hj Schmiedeberg 

 and others, and which had been attributed to special accelerator nerve 

 fibers. Heidenhain found that by stimulating the medulla oblongata 

 at different points, acceleration and augmentation, or slowing and 

 weakening, of the heart beat could be obtained. Gaskell traced in 

 the crocodile and frog the origin of the accelerator fibers to the sym- 

 pathetic system, and this was followed up by a more complete 

 anatomical investigation by Gaskell and Gadow. The innervation 

 of the heart of lower vertebrates was thus brought into line with that 

 of the mammal. In addition, he gave a more complete account than 

 had been given by Heidenhain of the cause of the independence of 

 the slowing and the weakening of the heart beat caused by pure 

 vagus fibers, and of the quickening and the increase of strength 

 caused by sympathetic fibers. A little later Gaskell showed that an 

 electrical change can be produced in quiescent heart muscle on stimu- 

 lation of the cardiac nerves, and that the change is different accord- 

 ing as the vagus or the accelerator nerve is stimulated. 



Gaskell's work in this field was of the first importance. His papers 

 are a storehouse of observations of a fundamental nature. He elab- 

 orated his theories and gave an admirable account of the whole sub- 

 ject in an article on " The Contraction of Cardiac Muscle " in 

 Schfifer's " Textbook of Physiology," published in 1900. It may be 

 mentioned that the rhythm of the heart was the subject of his 

 Croonian lecture to the Royal Society in 1881, and that on the work 

 mentioned above he was elected a fellow of the society in the follow- 

 ing year. 



In the course of his dissection of the accelerator nerve in mam- 

 mals, Gaskell was struck by the overwhelming preponderance of non- 

 meclullated nerve fibers in it, although the nerves centrally of ganglia 

 from which the accelerator fibers arose were mainly meduUated, and 

 this determined him to investigate the relation of the sympathetic 

 system to the spinal cord. At this timje the question of the relation 

 of the sympathetic and other peripheral ganglia to the cerebro- 

 spinal system was in a state of profound confusion, and general 

 agreement had been reached on a few points only. A great number 

 of facts had been described, and they covered a wide area of de- 

 scriptive anatomy in different classes of vertebrates, of histology of 

 nerve fibers and nerve cells, and of physiology. Few observers cov- 

 ered more than a small portion of the ground. Results were coming 

 quickly and the ground was tilled rather hastily. The practical dis- 

 appearance of the theory that the " vegetative " nervous system was 

 independent of the " animal " nervous system had led to the periph- 

 eral ganglia being less considered as a whole than they had been 

 at an earlier time, and to special explanations being put forward for 



