DEPARTMENT OF BOTANICAL RESEARCH. 



63 



which is a pentose presumably having some quaUties identical with 

 those of the mucilages of the plant. Dried cylinders and sheets of 

 this material were first subjected to the tests, being placed under the 

 auxograph after the manner in which disks of living material were 

 treated, as described in a previous paragraph. The results compared 

 with the swelling of gelatine were as follows: 



As the plant did not show water-relations which might be inter- 

 preted as a mechanical resultant of the separate action of gelatine or 

 agar, it was next proposed to test the reactions of a mixture in which 

 these substances would be blended. The first test-mass was one 

 which consisted of about 3 parts of agar and 2 parts of gelatine; both 

 were soaked and melted separately; then the gelatine was poured into 

 the hot agar, which was kept near the boiUng-point of water for a 

 half hour. The mass was then poured onto a glass slab for cooling. 

 Two days later it was stripped off as a fairly clear and transparent 

 sheet slightly clouded, the average thickness of which was 0.2 mm. 

 Strips about 5 bj'^ 7 mm. were placed under the apices of sheet-glass 

 triangles in glass dishes after the manner in which plant sections had 

 been tested, and auxographs were arranged to record the action of 

 acids, alkahes, and distilled water. 



The first trial, made on July 21, gave the following final relative 

 thickness of the strips as compared with the original: Distilled water 

 850 per cent; nitric acid (N/100) 725per cent ; hydrochloric acid (N/100) 

 750 per cent; sodium hydrate (N/100) 950 per cent. These results 

 were obtained while some enlargement was still in progress, but which 

 would not in the end disturb the relations given. A second test on 

 the following day at temperatures of 61° to 65° F. gave the following: 

 Distilled water 675 per cent; hydrochloric acid 625 per cent; nitric 

 acid 687.5 per cent; sodium hydrate 750 per cent. These results were 

 taken to be of such unportance that a series of mixtures of agar with 

 20, 50, and 80 per cent of gelatine by dry weight were made up. The 

 mixtures were poured into molds on glass plates and dried sheets from 

 0.1 nim. to 0.6 mm. thick were obtained. The first series of measLire- 

 ments given below includes the results of tests under varied conditions 

 not only of thickness of the samples, but also of temperature, length 

 of period of swelling, tension of instruments, etc. Each set of three 

 measurements of the swelling in the three liquids is therefore to be 

 considered separately. 



