324 THE BEGINNINGS OF LIFE. 



These transformations of the particles in the latex 

 of plants, and the somewhat similar transformation of 

 milk-globules, are most important and typical, since 

 the change takes place in comparatively large masses 

 of matter which can be watched with ease. It takes 

 place, moreover, in masses which, although they are the 

 products of living bodies, can scarcely themselves be 

 said to be Hiving ^' 



In the blood of animals we have another highly 

 nutritive fluid which might be supposed to be capable 

 of giving birth to independent living things under 

 certain conditions. It seems, however, to undergo such 

 changes more frequently in the lower forms of life than 

 in the higher. Amongst insects, several instances may 

 be mentioned in which simple organisms appear to be 

 born from the fluid constituents oi the blood, or else 

 produced by modifications of some of its already exist- 

 ing solid elements. 



This seems to be the case with ^ Muscardine,' the 

 disease which formerly committed such fearful ravages 

 amongst the silk-worms of France. 



^ There is, perhaps, most room for doubt, in the latter respect, con- 

 cerning the particles in the latex ; and these, being probably poor in 

 nitrogenous materials, evolve into very small and simple organisms. 

 The milk-globules, however, have a highly nitrogenous composition, 

 ovi^ing to an admixture of albuminoid constituents with their fatty ele- 

 ments — a combination which seems especially favourable for the occur- 

 rence of evolutional changes. The milk-globules accordingly are seen 

 to produce large specimens of Penicillmm of a remarkably vigorous 

 growth. 



