610 EXPERIMENT STATION RECORD. [Vol. 36 



ing it from potassium permanganate) to form an intermediate compoimd which 

 is a more energetic oxidizing agent than the original source of the oxygen. 

 The final stage in the oxidation is then effected by this intei*mediate compound." 



The relation between oxidase and catalase in plant tissues, G. B. Reed 

 (Bot. Gaz.. 62 (1916), No. 5, pp. 409-412. fig. i).— The juice of the pineapple 

 in three stages of ripeness (quite ripe and soft, yellow but not soft, and still 

 partly green) was examined for catalase, and the enzym found to be present in 

 the ripe fruits, with the greatest amount in the juice of the overripe but not in 

 the green fruit The juices from all of the fruits, however, showed approxi- 

 mately the same peroxidase activity. From the study with platinum black 

 noted above and from the fact that in certain stages of their development pine- 

 apples contain oxidases but no catalases, the author concludes that " the sub- 

 stances which effect the decomposition of hydrogen peroxid are not of necessity 

 concerned with the enzyms which accelerate peroxid oxidations. It may be 

 added that the fact that catalase is not universally present in living cells, as 

 Loew [E. S. R., 13, p. 115] and others suppose, has considerable theoretical 

 interest." 



The elasticity of the coag'ulum produced in cows' milk by rennet, O. Alle- 

 MANN and H. Schmid {Landw. Jahrb. Schweiz, 30 {1916), No. 3, pp. 557-385, 

 figs. 2). — A simple apparatus for determining the elasticity of milli curd, which 

 depends on measuring the resistance offered to the withdrawal from the coagu- 

 lated material of a device of three concentric rings attached to a vertical axis, 

 is described in detail. 



Because of the great importance of the elasticity of the curd in the manu- 

 facture of cheese, the authors studied, with the aid of this apparatus, the effect 

 of various factors on this property in the coagulation of milk. The results 

 showed that from the beginning of the coagualtion the elasticity of the curd 

 increased in direct proportion with the time. Variations in the amount of 

 rennet used, other conditions being the same, produced a direct increase in the 

 elasticity, depending on the amount used. For example, using double the 

 quantity of rennet in a given volume of milk the elasticity of the curd was 

 doubled. The elasticity of the curd also varied directly with the increase of 

 the acidity of the milk, and likewise with the addition of calcium chlorid. The 

 addition of ammonia, however, did not have the exact rever.se effect from that 

 of the acid, but, apart from decreasing the acidity, it appeared to exert a 

 detrimental effect on the enzym. 



An increase in temperature to a maximum of 41° C. increased coagulation 

 time. The elasticity of the curd was also directly proportional to the tempera- 

 ture increase, with no apparent maximum. Agitation of the material retarded 

 the coagulation time on an average of about 8 per cent. Previous cooling caused 

 some delay in the time of coagulation, and also a diminished elasticity of the 

 coagulum. 



The greatest factor influencing coagulation by rennet was found to be the 

 individuality of the milk. Great variations were observed, not only in the 

 coagulation time but also in the nature of the curd formed. The period of 

 lactation affected the coagulation time in that shortly after calving the time 

 increased, rapidly sinking, however, to a minimum, then again increasing in a 

 few days and remaining fairly constant. No apparent difference was observed 

 either in the coagulation time or nature of the curd produced by the morning 

 or evening milk of individual animals, nor did the feeding of various rations 

 produce any perceptible change. The milk from cows in fpstrus coagulated 

 much slower and produced a curd of reduced elasticity. Similar variations were 

 occasionally observed in the milk of animals which had been subjected to sudden 

 climatic changes. 



