CONDITION OF AGGREGATION OF ORGANISED STRUCTURES, 66y 



organised body, so that they act upon and decompose one another. It is certain 

 that all growth continues only so long as the growing parts of the cell are exposed 

 to atmospheric air ; the oxygen of the air has an oxidising effect on the chemical 

 compounds contained in the organised structure ; with every act of growth carbon 

 dioxide is produced and evolved. The equilibrium of the chemical forces is also 

 continually disturbed by the necessary production of heat; and this may also be 

 accompanied by electrical action. The movements of the atoms and molecules 

 within a growing organised body represent a definite amount of work, and the equi- 

 valent forces are set free by chemical changes. The essence of organisation and 

 of life lies in this : — that organised structures are capable of a constant internal 

 change ; and that, as long as they are in contact with water and with oxygenated 

 air, only a portion of their forces remains in equilibrium even in their interior, and 

 determines the form or framework of the whole; while new forces are constantly 

 being set free by chemical changes between and in the molecules, which forces in 

 their turn occasion further changes. This depends essentially on the peculiarity of 

 micellar structure, which permits dissolved and gaseous (absorbed) substances to 

 penetrate from without into every point of the interior, and to be again conveyed 

 outwards. 



This internal instability attains its highest degree in chlorophyll-granules and pro- 

 toplasm. In the former chemical processes take place with great energy and activity 

 under the influence of light, such as the formation of the green colouring matter and 

 of starch ; and when deprived of light other chemical changes at once ensue, which 

 terminate only with the complete destruction of the entire chlorophyll-granule. The 

 remarkable properties of protoplasm, which we have already examined from different 

 sides in discussing the structure of the cell, attain their climax in its spontaneous 

 automatic power of motion, and in its capacity of assuming different forms and 

 changing both its shape and its internal state, and therefore of bringing into action 

 internal forces, even when corresponding impulses from without cannot be observed. 

 It is impossible to enter here in detail into the explanation of these remarkable facts; 

 but they will be understood, at least generally and to a certain extent, if it is borne 

 in mind that neither the chemical nor the molecular forces are ever in equilibrium in 

 the protoplasm ; that the most various elementary substances are present in it in the 

 most various combinations ; that fresh impulses to the disturbance of the internal 

 equilibrium are constantly being given by the chemical action of the oxygen of the 

 air ; and that energy is continually being set free at the expense of the substance of 

 the protoplasm itself, which must lead to the most complex actions in a substance of 

 so complicated a structure. Every impulse from without, even when imperceptible, 

 must call forth a complicated play of internal movements, of which we are able to 

 perceive only the ultimate effect in an external change of form. 



The destruction of the micellar structure of organised bodies may take place in 

 many different ways, and affords an insight into many physiological processes. 



The most important forces by which the micellar condition of organic substances 

 is permanently altered are changes in temperature, chemical reagents, and substances 

 which have a powerful attraction for water. But these agencies do not in general 

 cause destruction until they have exceeded a definite degree of intensity ; while dif- 

 ferent changes of temperature and different states of concentration of the reagents 



