150 BACTERIA IN RELATION TO PLANT DISEASES. 



Liquid maintained at 8o for 15 to 20 minutes did not complete digestion until the morning of 

 the 4th day. The control required 3 hours. In another case digestion was complete in 24 hours. In 

 liquid maintained at 78 to 83 C. for 30 minutes digestion did not take place within 4 days, and in 

 that kept at 8o for the same time there was no indication of digestion within a week, while the control 

 required only 5 hours. From this Vines concluded that the digestive power had been destroyed. 

 Boiling for several seconds decreased but did not destroy the digestive power; for its complete 

 destruction the liquid must probably be kept at ioo for 3 to 5 minutes. 



Sodium carbonate was used exclusively in the experiments with alkali. To a quantity (5 to 

 10 cc.) of pitcher liquid an amount of the solid salt was added requisite to produce the desired 

 alkalinity. After this the liquid was placed in the incubator, for a given time at a given temperature, 

 then neutralized, then acidified with hydrochloric acid, and a digestion experiment was made. 



Results proved to be dependent on the following three factors: (1) the degree of alkalinity 

 (2) the duration of alkalinity, and (3) the temperature maintained during alkalinity. 



Treatment with 0.5 per cent to 5 per cent sodium carbonate at 35 to 38 C. for periods varying 

 from 30 minutes to 1 7 hours (the longer periods were used with the lesser degrees of alkalinity) always 

 retarded digestion, though in every case it took place eventually. In the case of treatment with 5 

 per cent sodium carbonate for 3 hours digestion required 26 hours. This led Vines to experiment 

 further with this degree of alkalinity, but at a higher temperature. He found that at 50 C. alkalinity 

 for 45 minutes greatly retarded digestion, while exposure 1.5 hours destroyed the digestive power; 

 /. e., there was no action within 6 days. Treatment with 1 per cent sodium carbonate for 1 and 1.5 

 hours gave results indicating that treatment with 1 per cent sodium carbonate for 1 hour at 50 C. 

 is an approximate index to the stability of the enzym. 



When pitcher liquid was passed through a Berkfeldt-filter it lost its acid reaction and its colora- 

 tion, and proved far less active as a digestive agent. To test the value of this fact as evidence for 

 the bacterial explanation Vines tested the effect of such filtration on liquids containing pepsin and 

 ptyalin. These were affected in much the same way; the digestive power was very much reduced. 

 Hence, if absence of the activity of pitcher liquid is due to removal of the bacteria, that of the gastric 

 juice and saliva must be attributed to the same cause. 



Vines states also that he has confirmed his results of 1877, when he demonstrated the presence 

 of a zymogen in the glandular tissue of the pitcher. His experiments were conducted as follows: 



He opened and washed out two unopened pitchers of N. mastersiana (the pitcher liquid was 

 strongly acid), and cut up the glandular part into fine pieces. Half of it, A (8 grams), was rubbed 

 up in a mortar with 20 cc. of distilled water; the other half, B, was rubbed up with 20 cc. of 0.25 

 per cent solution of hydrochloric acid. Both A and B were then placed for 45 minutes in the incu- 

 bator at 50 C. The liquid was then poured off, the substance dried somewhat, with blotting paper, 

 and then each was rubbed up with 20 cc. of glycerin. Eight days later digestion experiments were 

 made with the glycerin extract with the result that the acid extract caused complete digestion within 

 8 hours while the neutral extract required 48 hours more. In another experiment, in which the 

 material was treated with 0.5 per cent acetic acid at about 15 C. for 24 hours, the acid extract 

 digested more rapidlythan the neutral but the difference was notso marked as in the preceding case. 



In a later experiment, the pitcher material was divided into three parts, two were treated as in 

 the above experiment, and the third was rubbed up at once with glycerin. Digestion experiments 

 were made with the glycerin extracts. In this case the tubes were kept in the incubator at 36 C. 

 The fibrin in the acid extract had undergone solution in 30! hours, that in the neutral extract required 

 more than 3 days, while the third showed no sign of digestion at the end of 3 days. 



From these results Vines draws the conclusion that a zymogen is present in the glands, from 

 which an enzym is liberated on treatment with acid. He admits, however, that he has not always 

 obtained these results. In some cases treatment with acid decreased instead of increasing the activity 

 of the glycerin extract. This he thinks is due to the method of treating the pitcher material. The 

 most effectual mode of decomposing the zymogen is to act upon the tissue with acid for a short time 

 with a relatively high temperature (50 C). He thinks also, that, while the acid of the pitcher liquid 

 is useless for digestive purposes until the opening of the pitcher, it is probably of importance in that 

 it acts upon the zymogen, liberating the enzym. 



While investigating the nature of the ultimate products of digestion, Vines found indications 

 of the presence of peptone, which he had before failed to demonstrate. By using Kiihne's method 

 for separating dcutero-albumose and peptone he had no difficulty in demonstrating a true peptone. 

 Ramsden, who had suggested this method, also found peptone present in the digestion products 

 which he tested. The presence of leucin was confirmed. 



In conclusion, Vines classifies the enzym concerned as a tryptic ferment, differing from the 

 trypsin of the pancreatic juice in requiring an acid medium for its digestive action. It resembles 

 that of the germinating seed, but is more rapid and energetic in its action. 



