ALBUMINS OR PROTEINS. 199 



place is evident from the fact that the vegetation which has grown for 

 thousands of years still continues doing so in the customary manner, in 

 spite of the leaching of the mainland which has taken place. There is 

 practically no difference in the behavior of the plants and animals of the 

 ocean and those of the mainland. Marine plants assimilate carbon dioxide; 

 this process also requires the assistance of the sun's energy, which accounts 

 for the absence of plant life at great depths to which the sun's rays cannot 

 penetrate. Marine plants also require nitrates for the formation of their 

 albuminous constituents. The fishes in the ocean also obtain their albu- 

 min ultimately from the vegetable world. Marine vegetation is incapable 

 of utilizing all of the immense amounts of nitrogen presented to it. Nitro- 

 genous compounds are set free from dead plants and animals through 

 putrefactive processes. These are changed into ammonia, which then goes 

 over into nitrites and nitrates in the same manner as on the mainland. 

 The ocean occasionally casts large masses of sea-weed on the shores. The 

 amount of nitrogen from this source is infinitesimal in comparison with that 

 leached from the soil. It is, therefore, of great interest to learn that the 

 ocean also possesses denitrifying bacteria, which are continually setting 

 nitrogen free. They complete the cycle of the nitrogen washed into the 

 ocean as nitrogen compounds. 



The significance of the great value of the denitrification process now 

 becomes apparent, in contradistinction to its undesired appearance in the 

 soil. The great part which the nitrogen-assimilating bacteria play in 

 nature, is now explained. The living requirements of the whole world of 

 organisms guarantee an interchange of material! These smallest living 

 beings furnish us with the fundamental requirements of our existence. 

 The discovery of the denitrifying bacteria has also solved an apparent 

 contradiction. It is well known that the concentration of plant and 

 animal life on the mainland diminishes from the equator towards the 

 poles. This is not the case in the ocean. This circumstance is very strik- 

 ing, as one would be led to expect much better development of conditions 

 in the tropical seas, owing to the great preponderance of light, in com- 

 parison with the dark arctic regions. It is probable that this state of 

 affairs may be traced to the denitrifying bacteria in some manner. A 

 tropical environment is ideal for them and their activities. They develop 

 to best advantage at a temperature of 25-30C. They would, there- 

 fore, abstract more nitrogen from marine plants in tropical seas, than in 

 the seas of the arctic zone. We will at once state that this is merely offered 

 as an explanation. We know that the growth of all organisms is governed 

 by the Law of the Minimum, i.e., of all the substances which are accessible 

 to the organism, the amount utilized is governed by the amount of that 

 substance present to the smallest extent. While the marine plants may 

 have a large quantity of available nitrogen in the form of nitrates, it may 



