SYNTHESIS OF THE ALBUMINS. 27 



a class of bodies which occur widely distributed in both the animal 

 and the vegetable world, and form the groundwork, so to speak, of 

 all living matter. Like the carbohydrates and fats, they also con- 

 sist of carbon, hydrogen, and oxygen, but in addition to these ele- 

 ments nitrogen and variable amounts of. sulphur are constantly 

 present. To this class belong such bodies as serum-albumin, egg- 

 albumin, casein, fibrin, etc. They are exceedingly complex sub- 

 stances, and have a very high molecular weight. For vitellin, for 

 example, Bunge obtained the formula C y92 H. 48l N 9() O 8& S 2f which would 

 correspond to a molecular weight of at least 7557. 



The exact manner in which the albumins originate has not been 

 determined, and the many attempts which have been made to effect 

 the synthesis of bodies belonging to this class have been fruitless. 

 We are in possession of a number of observations, however, which 

 permit of an insight, at least, into the manner in which plants are 

 capable of elaborating these complex substances from the simple 

 material which serves as their food, and there is reason to suppose 

 that the synthesis of the albumins also takes place, to a certain 

 extent at least, in the chlorophyl-bearing portions of plants. 



It was formerly supposed that the nitrogen necessary in these 

 synthetic processes was furnished plants in the form of ammoniacal 

 salts. Subsequent investigations have shown, however, as has been 

 indicated, that this is usually not the case, and we now know that 

 through the activity of various bacteria in the soil the nitrogen 

 required by plants is here oxidized to nitrates. These are absorbed 

 and carried to the chlorophyl-bearing portions of the plant, where, 

 as we have seen, formic aldehyde and glucose are constantly being 

 formed. Here, or in the rootlets, a certain proportion of the nitrates 

 is apparently transformed into nitric acid, which is then promptly 

 reduced by the formic aldehyde, with the formation of a certain 

 amount of hydrocyanic acid, as shown in the equation : 



2HN0 3 + 5CH 2 O = 2HCN + 3CO 2 + 5H 2 O. 



In this form, then, the nitrogen probably enters into the construc- 

 tion of the albuminous molecule. This supposition is strengthened 

 by the observation that hydrocyanic acid, as such, or in the form of 

 cyanides, occurs widely distributed in the vegetable world, and is 

 characterized by the readiness with which it combines with a large 

 number of organic substances to form highly complex chemical com- 

 pounds. A study of the decomposition-products of the various 

 albumins further shows that their molecule can be reduced to urea, 



XNH CO-NH 2 



CO\ ATTT 2 , and oxamide, | , the hydrogen atoms of which 



CO NH 2 

 have either entirely or partly been replaced by the chains 



CO CH 2 CH 2 CH NH CH 2 CH NH CH 2 COOH. 



On studying this chain more closely, it will be observed that the 



