THE DEEPENING OF PHYSIOLOGY. 313 



the activities of the cells. ^' Consideration of the 

 individual functions of the body urges us constantly 

 toward the cell. The problem of the motion of the 

 heart and of muscle-contraction resides in the muscle- 

 cell ; that of secretion in the gland-cell ; that of food- 

 reception and resorption in the epithelium-cell and 

 the white blood-cell; that of the regulation of all 

 bodily activities in the ganglion-cell. If physiol- 

 ogy considers its task to be the investigation of vital 

 phenomena, it must investigate them in the place 

 where they have their seat, i.e., in the cell." * 



The central idea of cellular physiology was clear 

 long before its realisation began to be effected. In 

 1838, Schleiden said: ^^ Each cell leads a double life: 

 an independent one, pertaining to its own develop- 

 ment alone; and another incidental, in so far as it 

 has become an integral part of a plant.'' In 1839, 

 Schwann said : " The whole organism subsists only 

 by means of the reciprocal action of the single ele- 

 mentary parts." In 1858, Virchow said: "Every 

 animal appears as a sum of vital units, each one of 

 which bears with it the characteristics of life." But, 

 although the general idea was thus more or less clear 

 at the dates cited, the special study of the physiology 

 of the cell is much more modern. 



One of the shrewdest and keenest of the pioneers 

 of cellular physiology was Prof. John Goodsir, who 

 in 1842 communicated to the Royal Society of Edin- 

 burgh a memoir on secreting structures, " in which 

 he established the principle that cells are the ultimate 

 secreting agents; he recognised in the cells of the 

 liver, kidney, and other organs the characteristic 

 secretion of each gland. The secretion was, he said, 

 situated between the nucleus and the cell wall. At 



Max Verworn, General Physiology, trans. 1889, p. 48. 



