96 



D. T. MacDOUGAL 



This complex biocolloid high in nitrogen and in the nutritive 

 salts displays a capacity in swamp water superior to that shown 

 in bog water or pure water. The properties in question would 

 enable a plant so equipped to thrive in the waters of swamps 

 and it would be interesting to determine whether such a condition 

 actually prevails in the plants of the sedgy swamps. 



The earlier attempts to interpret the swelling action of proto- 

 plasm were founded on the assumption that such increase might 

 be represented by the action of gelatine. The unsoundness of 

 this assumption and the inadequacy of the methods using this 

 material have been amply demonstrated by results previously 

 published. At one end of the scale stand some plants and some 

 plant structures high in protein compounds and low in pentosans 

 and these do show a behavior approximating that of gelatine. 

 This is illustrated by the following series in which sections of 

 gelatine plates 0.18 mm. in thickness were swelled at 15°C. 

 giving measurements as follows: 



It is to be seen that all of the solutions decrease the swelling 

 capacity of the agar below that displayed in distilled water, and 

 that the greater reduction in the nutrient solution is to be 

 attributed to the higher salt content. 



Plants of bogs and especially swamps are undoubtedly sub- 

 jected to great variations in the composition of the water by 

 reason of inundations and floods. It was therefore thought 

 pertinent to extend experiments begun in 1916 in which alterna- 



