5 2o THE POPULAR SCIENCE MONTHLY. 



whose presence would be injurious to the organism, we must also take 

 into consideration that we may not he able to attain our object by a 

 single process, but by a whole series of altogether different processes 

 only by a most careful observation of all these points can we arrive 

 at results which will allow us to draw conclusions with reference to 

 the corresponding processes in the body. 



It may appear remarkable that, in the syntheses which have been 

 made, these conditions were not considered ; but it must not be forgot- 

 ten that a chemist makes a synthesis for its own sake, unconcerned 

 whether he attains his result in the same manner as the organism. He 

 can only attempt the solution of this question when he knows the 

 steps by which the structure is built up. But in this respect we are 

 still far behind, for our knowledge of the chemical properties of the 

 bodies which we find in the organism is still very incomplete. The 

 substances which are most important in the economy of the organism, 

 the albuminoids, notwithstanding the labor and time employed, are 

 very little known, and the same may be said of other substances, such 

 as the bile, the nerve-substance, etc. We do not even know whether 

 the albuminoids and similar compounds have ever been obtained in a 

 pure state ; their composition is, therefore, only approximately known ; 

 the question, whether the ash which they leave on burning is an essen- 

 tial constituent or an impurity, still remains undecided, and a good 

 method for separating the different members of larger groups is a pious 

 wish. The changes and decompositions of these substances are only 

 known in general ; in many cases we know the final but not the inter- 

 mediate products, which are of the highest importance, as, without 

 doubt, the organism operates with these. Here, above all, it is neces- 

 sary to throw some light on the obscurity which surrounds this prob- 

 lem, and the necessity will best be shown by an example. If albumi- 

 noids are treated with digestive ferments, or with dilute acids, there 

 is at first produced a series of peculiar compounds still similar to the 

 albuminoids, called peptones. If the latter are exposed to the action 

 of strong acids or alkalies, they are finally decomposed into amido 

 acids ; at the same time carbonic acid, ammonia, oxalic acid, and other 

 simple compounds, are formed in small quantities. Although com- 

 pletely justified in assuming that the elements of water have been 

 taken up in these processes, it is not positively known in what relation 

 the peptones stand toward the albuminoids ; whether the peptones 

 produced from various albuminoids are different or identical, or whether 

 only one or several peptones are produced from each albuminoid ; 

 whether they are crystallizable or not ; whether the peptones are 

 directly decomposed into amido acids, or whether further intermediate 

 products are formed in short, we are only beginning those investiga- 

 tions which promise to give the most important results. 



Fortunately, the organism also contains more simple compounds, 

 which are well known, and the formation of which can be discovered 





