I have previously shown[122] the action of digestive ferments or enzymes to be notable in the case of pancreatin. A careful study of the behaviour of the digestive enzymes in the animal body shows, however, pretty conclusively, that they are all destroyed before the fæcal matter is discharged,[123] and, therefore, the enzymes in the dung are not from this source. [122] J.S.C.I., 1894, March 31, 218–221. [123] See Gamgee, Phys. Chem. 2. An attempt was made to filter the dung diluted with water through a Berkefeld filter, and thus obtain a clear filtrate containing all the enzymes and free from bacteria; it was found impossible to filter the liquid in this way. The method of Claudio Fermi[124] was also tried, but a clear filtrate could not be obtained. [124] Ann. de Micrograph, ii. [6], March 20, 1896. The author has succeeded in obtaining the enzymes best in the following manner:--About 150 c.c. of the above-mentioned “puer” was well mixed with an equal quantity of glycerin and allowed to stand for seven days; it was then capable of being filtered on a filter pump, although very slowly, and yielded a clear filtrate of a deep golden brown colour; the filtrate was poured in a thin stream into a tall vessel containing about 1500 c.c. of 98 per cent. alcohol. A copious flocculent precipitate of the albuminous matters and enzymes was thrown down, the alcohol was filtered off and the precipitate washed on the filter with absolute alcohol, and dried over sulphuric acid. The resulting amorphous body was of light brown colour, and became darker when exposed to the air. The amount obtained from 150 c.c. of dung was 0·55 grm. (3·66 grm. per litre). The body consists of a mixture[125] of all the enzymes existing in the dung along with other albuminous bodies. It has a very slight diastatic action on starch. 0·5 grm. in 100 c.c. of water at 35° C. had a very considerable reducing action on skin. A further experiment with 0·5 grm. of amine hydrochlorides, 0·5 grm. of enzymes and 100 c.c. of water, at 35° C. brought down a piece of limed sheep grain in 30 minutes exactly like puer; the reaction of the solution at the commencement of the experiment was faintly alkaline; at the end of the experiment it was considerably alkaline. [125] I did not consider it necessary to purify the enzymes, the object being to examine the action of the bacterial products apart from the living organisms. It was noted that the fæcal odour of the glycerin solution disappeared on standing for two or three weeks, and the solution smelt strongly of ethyl butyrate, the enzymes being still present.