Section V, 1920 [23] Trans. R.S.C. 



On the Mutual Precipitation of Dyes and Plant Mucilages 

 By Francis E. Lloyd, F. R.S.C. 



(Read May Meeting, 1920) 



It has become increasingly evident during the past very few- 

 years that the behaviour of the emulsoid contents of plant tissues, 

 aside from those of the living protoplasm, affect, in a probably complex 

 way, the internal economy of the organism. These, for the most part 

 pentose materials, among other behaviours, play a doubtless import- 

 ant part in growth, one factor of their activity being found in affecting 

 the distribution of the water as between themselves and other con- 

 tingent or associated colloidal (emulsoidal) masses, especially the 

 protoplasm. An important example in the field of animal physiology 

 of such behaviour is afforded by the role of gum (acacia) in gum-saline 

 solutions when injected into the vascular system after shock.^ In 

 the field of plant physiology, attention may be drawn to the work of 

 MacDougal, Spoehr, E. B. Shreve, and myself, briefly summarized 

 in the Year Books of the Carnegie Institution of Washington, to the 

 earlier work of Borowikow and of some others, therein cited, as 

 indicating the general importance of the subject of the role of colloids 

 in plants, and the scope of the studies already made. 



There are, however, many difficulties of observation — interpreta- 

 tion aside for the time being — which have yet to be compassed. These 

 have more recently been adverted to by H . A. Spoehr,^ who mentions 

 among others the difficulties of observation and identification of 

 carbohydrate emulsoids in tissues and their elements. It was during 

 initial investigation into this phase of the subject that the peculiar 

 relations to be presently described cam.e to light. 



Some years ago I found that mucilage bodies derived from the 

 cell wall by hydrolysis, as during abscission,^ appeared after treatment 

 with ruthenium red to have been flocculated. At the time no more 

 than a suspicion that the dye had been the casual agent was entertained. 

 This was enough, however, to direct my observation to the effect of 

 dyes in contact with emulsoids such as plant mucilages especially 

 when, in the summer of 1918, I endeavoured to find a satisfactory 

 specific stain for the mucilage of the cacti (Opuntia).* On this score 



1 Bayliss, M. M. Jour. Pharmacol, and Exp. Thera. 15 : 29-73. March, 1920. 



2 The carbohydrate economy of cacti. Carn. Inst. Wash. Publ. 289, 1919. 

 'Abscission in Mirabilis Jalapa. Bot. Gaz. 61 : 213. March, 1916. 



* Year Book Carn. Inst. Wash. 1918, p. 72. 



