Chap, vii Enzymes and their Action 411 



and 1884, and was determined by him to be tryptic in 

 character. It was examined subsequently by many workers, 

 particularly Davis in 1893, Sharp in the same year, and 

 Harlay in 1900. 



Bouchut discovered in 1880 a proteoclastic enzyme in 

 the juice of the common fig (Ficus Carica). It was investi- 

 gated in 1883 by Hansen, and more completely in 1890 by 

 Mussi. The latter writer named it cradina. A similar 

 agent was found by the writer in the juice of the fruit of 

 Cucumts utilissimus in 1892. Its properties were those 

 of a trypsin. 



Chittenden's enzyme, to which he gave the name bromelin, 

 was obtained from the juice of the ripe pineapple. Atten- 

 tion had been called to it in 1891 by Marcano, but it was 

 not completely investigated till it came into the hands of 

 Chittenden and his pupils. It was very completely studied 

 by them, and of its mode and conditions of action more 

 was ascertained than was the case with any other vegetable 

 proteoclast up to the end of the century. Like all the 

 others so far mentioned, bromelin is referable to the trypsin 

 group. 



A few other observations of the occurrence of proteo- 

 clastic enzymes were recorded, but they added little 

 to the results detailed. Marcano observed proteoclastic 

 power in the juice of the leaves of the Agave and of 

 certain fruits in 1884, but he did not prepare an enzyme 

 from them. 



The occurrence of enzymes of this type will be alluded 

 to later again, in connexion with the nutritive processes 

 of the so-called insectivorous plants. 



Among the lower plants they have been described by 

 Krukenberg in 1882, Bourquelot and Herissey in 1895, and 

 Halm in 1898, in various groups of fungi, and by Bitter 

 in 1887, Lauder Brunton, and McFadyen in 1889, Fermi 

 in 1891, and Duclaux in 1899, in various species of bacteria. 



