EFFECT OF BOG WATER ON SWELLING 



93 



mm. in thickness, were cut in the plane of the joint and placed 

 between two sheets of filter paper to one of which they adhered. 

 A second sheet was laid over them and the preparation placed 

 on a wire netting to dry without pressure. In six days the 

 thickness had been reduced to about 0.5 mm. and enough mois- 

 ture still remained to give the slices a leathery consistency. 

 Suitable sections free from visible fibrovascular tissue were pre- 

 pared which gave swellings as follows: 



These measurements ^vere taken at the end of twenty-four 

 hours when a fair rate of increase was still noticeable which 

 would in the end have carried the figures up to the next hundred 

 in the upper lines which gives the swelling in percentages of the 

 thickness of the dried sections. The lower line shows the pro- 

 portion to the original measurements of living material. The 

 swelling in bog water is but little less than in distilled water 

 and is also but little different from that in the nutrient solution, 

 which is of the concentration used in water cultures. Hydration 

 is how^ever noticeably less in swamp w^ater. 



The nutrient solution used in all of these tests was one made 

 up after Tottingham's formula including four salts as follows: 

 Potassium nitrate 1 M, di-potassic phosphate 2.38 M, magnesium 

 sulphate 2.97 M and calcium nitrate 2.95 M. 



Attention was now turned to the biocoUoids to ascertain 

 whether the action of plant material living and dried would find 

 a parallel in the action of mixtures of known composition. Sec- 

 tions of plates composed of agar (90) and oat-protein (10) w^ere 

 found to show the following swellings at 15°C. 



