Tito Carbone (60) found amongst the products of P. vulgaris, choline, ethylenediamine, gadinine, and trimethylamine. Macé (61), criticising Hauser’s work, considers the cocci form of Proteus to be spores. Bienstock (62) believes the rôle of the Proteus group somewhat doubtful. He discovered (1884) another widely distributed putrefactive organism, which he called Bacillus putrificus; it is a spore bearing, drumstick shaped bacillus found in fæces; it is anærobic and specially attacks fibrin. Now fibrin is extremely resistent to the action of most putrefactive bacteria, and it is very probable that specific organisms ferment the different albuminous compounds in the same way that the different carbohydrates are each decomposed by specific ferments. A certain number of species of bacteria are able to decompose both carbohydrates and proteids. Tissier and Martelly (70) call these mixed ferments, and divide them further into two groups (1), mixed proteolytic ferments, including B. perfringens, B. bifermentans sporogenes, Staphylococcus albus, Micrococcus flavus liquefaciens, Proteus vulgaris, this group decompose albumin by means of tryptic enzymes. (2) Mixed peptolytic ferments are only able to attack the albumin when it has undergone a preliminary decomposition. This group comprises B. coli, B. filiformis, Streptococcus pyogenes, Diplococcus griseus non liquefaciens. The second class of bacteria are those which are without action on carbohydrates, and only attack proteids; these consist of the true proteolytic bacteria B. putrificus, and B. putidus gracilis, and the peptolytic bacteria, Diplococcus magnus anaerobius and Proteus zenkeri, which can only decompose peptones. These authors state that B. putrificus is always present in putrefying albumin, but always accompanied by facultative ærobes which favour the growth and development of the special putrefactive bacteria. In the putrefaction of meat the reaction is first acid owing to the action of the mixed ferments on the sugars present. In the next stage ammonia is formed by the tryptic enzymes secreted by the ærobic bacteria, and so the anærobic organisms are enabled to develop. We can thus understand how it is that putrefaction proceeds more rapidly the more mixed ferments there are present, although these were formerly supposed to hinder putrefaction from taking place.