714 THE POPULAR SCIENCE MONTHLY. 



of the chemist, where organic matter goes through a series of gradual 

 modifications by which it is adapted to new artificial conditions ; and, 

 on the other hand, facts observed in the lowest orders of animals 

 by the biologist. We conceive that, in the primordial world, as now 

 in the laboratory, higher types of organic substance were formed at 

 the expense of lower types, and that gradually, after repeated reac- 

 tions and under favorable conditions, they resulted in organizable pro- 

 toplasm, a substance which is very susceptible of modification. Pro- 

 tein, as we know, may exist in upward of one thousand isomeric forms, 

 and, by combination with itself and with other substances, it yields 

 products still more complex, and in countless numbers. Hence we can 

 easily conceive how, under the conditions of heat and liglit tlien exist- 

 ing on earth, and with the aqueous, mineral, and atmospheric environ- 

 ment of that epoch, protein may have undergone metamorphoses with- 

 out end. Under conditions which we can conceive as possible, though 

 we may not be able to define them exactly, products may have been 

 evolved fitted to exhibit the rudimentary vital reactions. In this way 

 we till up the chasm which divides the positive chemical facts of the 

 higher organic combinations from the biological phenomena of the 

 lower forms of life. 



But another hypothesis is still necessary. " When we come down 

 to the substances out of which living bodies are formed, we find 

 groups and sub-groups of manifold and divergent compounds, the 

 units of which are large, heterogeneous, and unstable in a high de- 

 gree. Why should we suppose that these combinations must stand 

 still at the complex colloids which enter into the composition of or- 

 ganic matter ? Is it not more probable that, in addition to tliese col- 

 loids, there are developed by a higher combination atoms still more 

 heterogeneous and compounds still more numerous? If colloids are 

 unstable, extremely modifiable by very slight incident forces, and in- 

 capable of assuming the equilibrated form of crystallization, then a 

 fortiori these new organic atoms are unstable, very modifiable, and of 

 many different species." They would surpass pi'otein in instability 

 and plasticity as much as jDrotein surpasses organic matter. Further- 

 more, these atoms would possess one fundamental property, without 

 which no explanation is possible in biology, viz., the property of ar- 

 ranging themselves in certain forms peculiar to the various groups to 

 which they belong a property but little understood, though its ex- 

 istence is unquestionable. We call it polarity^ for want of a better 

 terra, to indicate the power of manifesting actions in a certain fixed 

 direction. These atoms we denominate physiological units. They 

 are developed in every living thing, differentiating themselves from 

 one another in different organisms by the same causes which differen- 

 tiate the organisms themselves, and in this way acquiring a diversity 

 which corresponds to that of the creature they constitute by their ag- 

 gregation. They follow, step by step, in their modifications the modi- 



