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E. B. GREEN ON ROOTS AND SOME GROWTHS UPON THEM. 



Root hairs are extensions of the walls of the outer circle of the 

 root cells, and continuous with them ; they spread out at their 

 base in some cases very considerably, but with this exception they 

 are tolerably uniform. They do not branch, but in some instances 

 divide into several short swollen projections at their extremities. 

 The hairs upon the roots of many ferns are of a rich orange brown 

 colour, but those of most plants are colourless or very slightly 

 tinted ; they are beautifully iridescent when viewed with a dark 

 ground illumination ; bright spots of organizable substance are 

 seen abundantly in some and very sparsely in others. 



They are very glutinous and attach themselves firmly to the 

 glass slide. I have examples which have withstood much rough 

 usage. They were put upon glass four or five years ago, and 

 although they were uncovered they have suffered very little injury, 

 but the roots from which they sprung have long since disappeared. 

 They cling to grains of sand and other mineral and vegetable 

 substances in the soil, and exercise a very powerful chemical 

 action upon them. They differ greatly in character, dimensions, 

 and quantity in various plants, being abundant and of consider- 

 able length in the grasses, ferns, and most annuals, and few and 

 short in fleshy rooted plants. 



The drawings of various hairs x 70 Will give some idea of 

 their different lengths, and others x 500 of their comparative 

 diameters and other characters. 



The dimensions of the longest hairs shown are as follows : — 



