Obituary Notices. 
xxxi 
In 1843, when physiologists were much occupied with the cell 
theory of Schleiden and Schwann, Donders carried on researches 
with Mulder, more especially in the chemical examination of the 
tissues while under the microscope. He also about this time came 
under the influence of the great German physiologist Johann 
Muller, whose doctrines, more especially those relating to the 
nervous system and the senses, have largely moulded the life-work, 
not only of Donders, hut of Helmholtz, Carl Ludwig, and many 
other physiologists in Germany. In these early years, also, he was 
much occupied with the study of the dynamical characters of living 
beings, and in a well-known paper on the Metabolism of Tissue as 
the Source of the proper Heat of Plants and Animals, he showed how 
the skin acts as a regulator of bodily temperature, and he discussed 
the relation between heat and work in the living tissues. The 
fame of Donders largely rests, however, on his researches on vision. 
In 1846 appeared a paper on the Movements of the Human Eye, 
and this was followed by many similar contributions through a 
series of years. In these papers, which were largely devoted to the 
problems of single vision, the nature of the horopter, the conditions 
of stereoscopic vision, and the mechanism of the movements of the 
eyeballs, Donders substantially laid the groundwork of our present 
knowledge of these subjects. He also wrote on the Relation between 
Convergence and Accommodation, the Regeneration of the Cornea, 
and on the Use of Lenses in the^Treatment of Squint. After a visit 
to London in 1851, when he became acquainted with the dis- 
tinguished ophthalmologist von Graefe, he resolved to devote his 
life chiefly to this department of the medical art, and for many years 
he enjoyed a large practice as an ophthalmic surgeon. For twelve 
years he edited the Nederlandsch Lancet , in the pages of which many 
important communications on ophthalmological subjects appeared 
from his pen. The great work of his life, however, was a volume 
entitled Anomalies of Refraction and Accommodation , a translation 
of which was published by the Hew Sydenham Society. Familiar 
with the researches of Gauss, Listing, and Helmholtz, Donders 
investigated mathematically and by experiment the optical conditions 
of the normal eye, and showed how these were modified in myopia, 
hypermetropia, and astigmatism. He also discussed theoretically 
the influence of age upon refraction and the mechanism of accom- 
