GENERAL PROPERTIES OF THE ECTOPLASM 



Red blood corpuscles are discs, measuring seven to eight by 

 two microns; they thus possess a large surface area, the 

 sum of which amounts in an adult man of 78 kilograms, 

 according to one estimate, to 3840 square meters. Hart- 

 ridge^ has suggested that the shape of the red blood corpus- 

 cle is the best possible one for insuring easy oxygen-intake. 



No one can object to the proposition that oxygen to enter 

 a cell must cross the cell-boundary. Even on the theory 

 that in oxygen-consumption only the most deeply located 

 structures of the cell, nucleus or otherwise, are concerned, 

 the oxygen enters the cell by way of the cell-surface. Rea- 

 soning by analogy we may say that just as there exist special 

 structures as gills and lungs to obtain oxygen, so in cells 

 generally the modified surface permits easy access of oxygen. 

 These surface-modifications are delicate prolongations. It 

 is also interesting to note that pigment granules, said to be 

 carriers of oxygen, line up at the cell surface. 



Oxidation means liberation of heat. The heat is lost 

 by the cell-surface. Here again the cell-surface is admir- 

 ably constructed for the rapid conduction and radiation of 

 heat. Since heat is produced when colloids take up water 

 and also when they liquefy, it may be that cell-surfaces in 

 breakdown through swelling and liquefaction liberate heat. 



Another fundamental property of living substance is 

 conduction. Any living cell when stimulated has the capa- 

 city to transfer the effect of this stimulus. The degree of 

 conduction constitutes one of the chief differences that dis- 

 tinguish animals from plants. In animals conduction is 

 the function of the nervous system, which possesses this 

 property, general to all cells, in the highest degree. 



Now among other characteristics of nerve cells we note 

 an extreme differentiation of the ectoplasm, as has been 

 stated. Nerve cells show one or more processes, some of 



Hartridge, ig20. See also Ponder^ ^934- 



iig 



