182 Proceedings of Royal Society of Edinburgh. [sess. 
which appeared when he was 35 years of age, he had devised his 
voltaic cell known as the “ Grove,” and other voltaic combinations. 
The “ Grove ” was in its day an important invention, as giving 
high electromotive force and moderate resistance. The polarisa- 
tion of gases occupied much of his attention, and he invented the 
gas-cell, interesting as the forerunner of the modern secondary 
battery. He received a medal from the Royal Society for his 
Paper on Voltaic Ignition and the Decomposition of Water , which 
formed the Bakerian Lecture for 1846. In 1871 he became a 
Judge, and shortly afterwards received the dignity of knighthood. 
He was D.C.L. of Oxford and LL.D. of Cambridge. He was 
elected a Fellow of the Royal Society of London in 1840, and a 
Fellow of this Society in 1881. He died August 2nd, 1896. 
When the Council requested me to deliver this opening address, 
they suggested that I might occupy a portion of it with an account 
of any recent investigations that have occupied my attention. It 
gives me pleasure to act upon this suggestion, and I therefore 
venture to bring under your notice a few subjects that have 
specially interested me during the last few months. 
The Structural and Physiological Nervous Unit. 
Up to a comparatively recent date, our conception of the nervous 
system was that it was built up of nerve cells and nerve fibres, 
more or less intimately bound together by a peculiar kind of 
tissue known as neuroglia. It was further supposed that, in the 
central nervous organs, nerve cells were linked together by pro- 
cesses passing from one cell to another, that sensory nerve fibres 
passed into, and were in their substance continuous with, nerve 
cells, and that motor fibres originated in nerve cells, and passed out 
to muscle fibres. It was also held that the elements of sensory 
organs, such as the retina or the organ of Corti, were organically 
connected with nerve cells in the cerebral organs. In short, the 
nervous system, as a whole, was held to be composed of cells and 
fibres closely connected together, so that the structure was like a 
vast web, the size of the meshes of which would vary according to 
the intricacy of the connections by which the various cellular 
elements were held together by nerve fibres. These histological 
