20 GENERAL PHYSIOLOGY 



isms with mathematical contours are very numerous (radiolaria) and 

 many of them do not exhibit a differentiation of their protoplasm nor 

 a division of function (amoeba). Upon the genetic basis, it is usually 

 stated that organisms can only originate from organisms. But if we 

 adhere to that theory regarding the origin of life which assumes that 

 the first cell arose in consequence of a combination of inorganic sub- 

 stances at a time when conditions upon this earth permitted this union 

 to take place, ^ this difference cannot be said to be of fundamental 

 importance. It is conceivable that living matter appeared as a result 

 of the evaporation of water containing the common salts. In the 

 course of this concentration cyanides and other similar organic com- 

 pounds were formed in consequence of vigorous electrical disturbances. 

 These elementary organic globules eventually gave rise to cells and 

 by descendance to all the organisms inhabiting this earth. ^ It is a 

 well-known fact that inorganic substances are constantly made use of 

 by plants in their production of organic material and lastly, it must 

 be taken into account that not all organisms give rise to their like. 

 For example, the workers of the bees and ants are sexually retrogressive 

 and do not possess the power of reproduction. 



The statement has also been made that living substance possesses 

 the properties of irritability and contractility, while inorganic material 

 does not. But if we observe an ordinary reaction between substances 

 occurring in a test tube, we cannot fail to recognize that even inorganic 

 matter is receptive and gives rise to motion. This is especially true 

 of those substances which cause reactions of an explosive kind, such as 

 nitroglycerin. The energy liberated by this body when stimulated, 

 can scarcely be duplicated, and hence, with the exception of the fact 

 that inorganic material presents an irritability and contractility of a 

 type somewhat different from that shown by living substance, this 

 ba^sis does not furnish an actual means of differentiation. 



If living substance is studied from the standpoint of chemistry, it 

 is found that it contains certain organic bodies the complexity of 

 which is not equalled in the inorganic world. Indeed, one of these 

 groups, the proteids, forms a constant constituent of protoplasm, while 

 no substance can be found in the inorganic world, which at all ap- 

 proaches the complexity of the proteid molecule. It is true, however, 

 that even this difference must disappear as soon as a way has been 

 found to produce these bodies artificially. There is one peculiarity, 

 however, which is decisive and that is the specific metabolic function 

 of living matter. Not only is it capable of altering its composition 

 constantly, but also of giving off certain waste products which are 

 subsequently replaced by new material. Life, therefore, is character- 

 ized by nothing more than a specific metabolism of certain substances 

 and especially of the proteins. In a very general way, however, it is 

 permissible to state that hving substance is distinguished from life- 



1 Preger : Die Hypothesen iiber den Ursprung des Lebens, Berlin, 1880. 



2 E. Hackel : Gen. Morph. der Organismen, Berlin, 1866. 



