NATURE AND CONDITIONS OF LIFK. 7 



conductors of electricity, and certain other forms, such as 

 glass, are non-conductors, we are in truth saying that elec- 

 tricity requires for its manifestation a certain " physical 

 basis." Upon merely theoretical grounds, therefore, we 

 might have assumed the existence of a "matter of life," or 

 a physical basis absolutely necessary for the manifestation 

 of vital phenomena. This physical basis of life is known 

 by the now notorious name of "protoplasm," or, as it is 

 better termed by Dr Beale, "bioplasm." 



As regards its nature, protoplasm, though capable of 

 being built up into the most complex structures, does not 

 necessarily exhibit anything which can be looked upon as 

 organisation or differentiation into distinct parts ; and its 

 chemical composition is the only constant which can be 

 approximately stated. It consists, namely, of carbon, oxy- 

 gen, nitrogen, and hydrogen, united into a proximate com- 

 pound to which Mulder applied the name of "proteine," 

 and which is very nearly identical with albumen or white-of- 

 egg. It further appears probable that all forms of proto- 

 plasm can be made to contract by electricity, and "are 

 liable to undergo that peculiar coagulation at a temperature 

 of 4o°-5o° centigrade, which has been called ' heat-stiffen- 

 ing ' " (Huxley). Protoplasm, therefore, may be regarded 

 as a general term for all forms of albuminoid matter ; and, 

 in this general sense, we may safely assert that protoplasm 

 is the " physical basis " of life ; or, in other words, that vital 

 phenomena cannot be manifested except through the me- 

 dium of a protoplasmic body. It is to be borne in mind, 

 however, that it has not yet been shown that all the forms of 

 matter which we include under the conveniently loose term 

 of " protoplasm," have a constant and undeviating chemical 

 composition. It must also be remembered that there are 

 certain other substances, such as some of the mineral salts, 

 which, though only present in small quantity, nevertheless 

 appear to be absolutely essential to the maintenance of life, 

 at the same time that their exact use is not at present known. 



