THE COMPONENTS AND COLLOIDAL BEHAVIOR OF 



PLANT PROTOPLASM. 



By D. T. MacDOUGAL and H. A. SPOEHR. 

 (Read April 23, jg2o.) 



Summary of Generalizations Previously Discussed. 



The principal conclusions established by our previously described 

 investigations which are of direct interest with relation to new re- 

 sults to be presented are as follows : 



I. The protoplasmic mass of the active cell of the plant is a 

 mixture of carbohydrates chiefly in the form of pentosans and al- 

 buminous substances, with a probable very low but undetermined 

 proportion of lipins. In addition to the mucilaginous substances of 

 the first, freely soluble sugars may be present in the cell solutions. 



II. The principal components of plasmatic masses, the mucilages 

 and the proteins, are mutually non-interdifi^usible and hence when 

 brought together in the cell by minute accretions or mixed in liquid 

 form must be taken to form complex emulsions or mesh-works, and 

 to occur separately both in disperse phase and disperse medium. 



HI. Of the components of such a mass the one which could be 

 regarded as the more solid as having the lesser attraction for mole- 

 cules of water, would tend to take position in the peripheral layer 

 and to assume a greater density by lessening the liquid phase in the 

 surface layer. 



IV. The external layer of any colloidal mass or of any layer 

 where two masses meet has invariably a composition determined by 

 the constitution of the impinging masses. The formation of the 

 cellulose wall which is first seen as a free plate between two separat- 

 ing protoplasts has a structure resulting from such action. The 

 plasma of the plant being highly carbohydrate, the external layer is 

 consequently largely anhydride of this material. The layers added 

 internally to the initial wall must be of the same character. Further- 

 more for similar reasons, the external layer of the plasma, the semi- 

 permeable membrane, would also be high in carbohydrate. The en- 



150 



