GLUCOSIDES 93 



BIOLOGICAL SIGNIFICANCE OF GLUCOSIDES 



The bitter taste of glucosides and their almost universal 

 presence in the bark of plants undoubtedly helps to prevent the 

 destructive gnawing of the bark by animals. 



Glucosides having either, a strong bitter taste, or pronouncedly 

 poisonous properties, likewise undoubtedly serve to protect such 

 important organs of plants as the seeds and fruits from being 

 prematurely eaten by birds and animals. The common disap- 

 pearance of these bitter substances as the seed or fruit ripens 

 adds to the attractiveness of the material for food for animals at 

 the proper stage of ripeness to provide for wider distribution of the 

 seeds for further propagation. Further, the very general occur- 

 rence of these protective glucosides in many of the vegetative 

 parts of plants during the early stages of growth, followed by their 

 disappearance after the seeds of the plant have been formed, 

 certainly serves to protect these plants from consumption as forage 

 by animals before they have been able to develop their reproductive 

 bodies. The lack of palatability, and even the production of 

 digestive disorders resulting from the eating of unripe fruit may 

 be due, in part at least, to the presence of protective glucosides in 

 unripe fruits and vegetables. 



On the other hand, the almost universal presence of the bril- 

 liant pigment glucosides in the external parts of flowers undoubt- 

 edly serves to attract the insects which are biologically adapted to 

 provide for the transportation of *pollen from one blossom to 

 another and so to insure the cross-fertilization which is so impor- 

 tant in maintaining the vigor of many species of plants. 



It is apparent that this important group of compounds, with 

 its exceedingly varied and complex constituent groups, may play 

 a variety of significant roles in plant growth. 



REFERENCES. 



ARMSTRONG, E. F. "The Simple Carbohydrates and Glucosides," 239 pages, 



Monographs on Biochemistry, London, 1919 (3d ed.). 

 VAN RUN, J. J. L. "Die Glykoside," 511 pages, Berlin, 1900. 



