210 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1916. 



very great number of chains, some of which are formed wholly of 

 carl3on atoms, others of atoms of carbon and of nitrogen, but which 

 for the most part are of closed chains. The albumens obtained from 

 dead tissues are therefore of cyclic structure. 



Is it the same with those albumens which still form an integral 

 part of living protoplasm ; and how do we know this? A very inter- 

 esting observation of Loew will be offered as a beginning of my 

 answer to these questions. Loew has stated that all those chemical 

 reactions which in ^dtro are susceptible of attacking the aldehydes 

 and the primary bases, or which act on the aldehyde and aminogen 

 groups which characterize them, that all these reactions, are inva- 

 riably poisonous to living protoplasm. These same reactions are, 

 on the other hand, without any influence on dead albumen. Loew 

 logically concludes from this that the molecule of living albumen 

 incloses the said groups, while the molecule of dead albumen no 

 longer possesses them. 



These two groups of atoms, throughout the whole extent of or- 

 ganic chemistry, possess some very active though opposite character- 

 istics which tend to react upon one another by an interchange of 

 their elements. This exchange does not take place in living albumen, 

 since the two groups are here in a coexistent state; this becomes 

 effective on the death of the cell, for neither of the two groups can 

 any longer be discovered in dead albumen. 



The stabilization of the protein molecule would therefore be due, 

 according to Loew, to the saturation of the one by the other of these 

 two groups. This observation appears capital to me; but its author 

 has not at all, it seems to me, followed the conclusions to their end. 

 I will try to do this for him. 



On account of their very nature these groups of atoms of which 

 I speak could not in any case form an integral part of a closed 

 chain. Both being monovalents they could form part only of open 

 chains. Their existence in living albumen, therefore, necessarily 

 implies the presence of these chains. But the union of two atomic 

 groupings forming part of an open chain could not be made unless 

 there was a closing of this chain ; at the same time the disappearance 

 of two active groups necessarily also involves the loss of a part of 

 the activity of the resultant complex, just as a man who joins his 

 hands or crosses his arms loses to a great extent his means of action. 



The stabilization of living albumen, therefore, involves a cyclisa- 

 tion. In closing the open chains in themselves the albumen of the 

 cellular protoplasm enters into equilibrium and repose. Its period 

 of activity is ended in the same way as that of all the substances 

 which have contributed to its maintenance. For those and the 

 others cyclisation is death. 



