Febbuaky 19, 1904.] 



SCIENCE. 



315 



Vista, Colorado. Mr. F. E. Marsh, of Deru'er, 

 first called my attention to the fact that the 

 roots of one of our native plants contained 

 rubber, and kindly supplied me with material 

 for experiments. 



The roots tested were found to contain from 

 five to twelve per cent, of crude rubber. This 

 product is soluble in carbon bisulphide and 

 benzol; it burns, giving off a strong odor of 

 rubber. Several tests were made which 

 showed that powder made from the bark con- 

 tained a much larger per cent, than that made 

 from the whole root. The crowns, when 

 cleaned, contained about the same per cent, 

 as the roots ; the wool-like material surround- 

 ing the crovrais contained a small per cent, 

 though it was not so elastic as that taken 

 from the roots and crowns. 



The stems and leaves contained a resin sol- 

 uble in carbon bisulphide, but it was a brown 

 inelastic mass and when burned lacked the 

 characteristic odor of rubber. The seeds con- 

 tained a resin that superficially resembled 

 that found in the stems. 



It is hoped that the occurrence of rubber in 

 the permanent parts of this Picradenia and 

 not in the parts lasting only through the sea- 

 son may add to our knowledge as to the use 

 of this substance. A detailed report on the 

 physiological structure of these roots will be 

 made as soon as fresh material can be ob- 

 tained. WiLMATTE Porter Cockerell. 



Colorado College, 



BOTANICAL NOTES. 



PROGRESS IN FORESTRY INSTRUCTION. 



It is but a few years since American uni- 

 versity professors have given serious attention 

 to that department of botany which deals 

 with trees, i. e., forestry, and it is a good sign 

 of a broadening view of the work of the uni- 

 versity and its relation to the community that 

 not only are courses in forestry now offered by 

 a considerable number of colleges and univer- 

 sities, but in addition their professors are 

 Writing books on the subject. Trees are no 

 longer regarded by the botanist as mere species 

 having place in a scientific system of classi- 

 fication, and on a definite portion of the 

 earth's surface. These facts are important; 



fully as important as they have ever been, but 

 we have learned that these giant plants have 

 other interesting relations. We have found 

 it as interesting to study the biology of a pine 

 or an oak as of a microscopic alga or fungus. 

 How to grow a tree is as legitimate a subject 

 of inquiry as how to grow a particular bac- 

 terium or saprophytic fungus. The ecology 

 of the forest affords as many interesting prob- 

 lems as the study of the zones and belts of 

 ponds and swamps. 



A little more than five years ago Professor 

 Green, of the University of Minnesota, pre- 

 pared a little book under the modest title of 

 ' Forestry in Minnesota,' of which an edition 

 of 10,000 was published by the Minnesota 

 Forestry Association. After about three 

 years, this edition being exhausted, Professor 

 Green prepared a second which was published 

 as a bulletin of the Geological and Natural 

 History Survey of Minnesota. He has now 

 revised the book again, enlarging and making 

 it more general, so as to adapt it to the whole 

 of the United States. Its title is now more 

 general also — ' Principles of American For- 

 estry ' — and it bears the imprint of John . 

 Wiley, of New York. 



The scope of the book may be learned from 

 an enumeration of the principal chapter head- 

 ings, as follows : ' The Tree and Tree Growth ' ; 

 ' The Forest ' ; ' Forest Influences ' ;. ' Forest 

 Regeneration ' ; ' Propagation ' ; ' Forest Pro- 

 tection ' ; ' Rate of Increase in Timber Trees ' ; 

 'Uses of Wood'; 'Durability'; 'Forest Eco- 

 nomics ' ; ' The Important American Timber 

 Trees ' ; etc. 



A single quotation from the chapter on 

 forest regeneration will sufiice to show at once 

 the style of treatment and the considerable 

 botanical interest that this study involves, as 

 presented in this admirable book: 



Succession of tree growtli is an expression some- 

 times used as though there were a natural rota- 

 tion of trees on the land. There is nothing of the 

 sort. Sometimes hardwoods will follow pine, or 

 the pine the hardwoods, where the two were 

 mixed at the time of cutting, and there was a 

 yovmg growth of one or the other kind which had 

 a chance to grow when its competitor was re- 

 moved. Where land is severely burned after be- 

 ing cut over, the trees that show first are gen- 



