68 
Proceedings of Royal Society of Edinburgh. [sess. 
The Presence of Enzymes in Normal and Pathological 
Tissues. By John Souttar M ‘Kendrick, M.D.* 
(Read December 18, 1899.) 
The unorganised ferments or enzymes which are present in the 
digestive juices have for many years occupied the attention of 
physiologists. Although their chemical nature is still doubtful, 
yet most of their physical and chemical characters are known, and 
there are methods by which they may be extracted from the tissues 
and digestive juices. They are generally believed to play the 
most important part in the digestive process, and within recent 
years physiologists and pathologists have speculated as to the 
existence of similar substances in other tissues, and so have 
endeavoured in many instances to offer a hypothetical explanation 
of some of the changes that occur in tissue cells themselves. 
During the last eighteen months I have endeavoured to ascertain 
the presence or absence of these enzymes in normal and 
pathological tissues generally. Before describing the method 
adopted in carrying out this research, with the enumeration of the 
tissues examined and the results obtained, I shall briefly refer to 
our present knowledge of the existence of these enzymes in tissues 
other than those of the digestive tract, as well as to their presence 
in plants. 
Do Enzymes Exist in other Tissues'? 
Zymolysis, one of the manifestations of the digestive process, 
occurs in plants as well as in animals. We know from the re- 
searches of Bernard f that digestion in plants is in most cases an 
interstitial one. By that term he meant the chemical changes 
that take place in the food stored up in the tissues for purposes of 
nutrition. Eor example, the starch that exists in the tuber of the 
potato undergoes conversion into sugar at one period of its growth. 
* This is an abstract of the original paper. The research was conducted partly 
in the Physiological Laboratory of the Glasgow University, and partly in a 
laboratory of my own at home. 
t Lemons sur les phenomenes de la vie, T. 2, 1879, Paris. 
