128 



NOTES AND COMMENT 



beings, but it is only because chemistry still lags so far behind physics 

 in the synthesis of organic forms." — D. T. M. 



The Cambridge University Press announce the appearance of a vol- 

 ume entitled Herbals — ^Their Origin and Evolution, by Agnes Arber, 

 Fellow of Newnham College. The history of the printed herbal is 

 traced from 1470 to 1670, both from the botanical standpoint and that 

 of the art of illustration. 



The fifth Bulletin of the Geological and Biological Survey of South 

 Dakota contains papers on the geology and geography of the bad-land 

 region in the southern part of the state, together with an account of its 

 floristic ecology and a list of its flora, by S. S. Visher. 



Considerable success has attended the experiments in afforestation 

 which have been carried on for several years by the Forest Service in 

 the sand hill region of north-western Nebraska (Forest Service Bulletin 

 121). This region, which makes one-fourth of the area of Nebraska, 

 is covered by a scant growth of grasses and is almost devoid of trees. 

 Its rainfall is from 15 to 26 inches a year, and its surface soil usually 

 possesses less than 1% of organic matter. The western yellow pine and 

 the jack pine have been the most successful trees in the experimental 

 plantings. The former of these now has its eastern limit of distribution 

 just west of the sand hills, but remains of it have been found well within 

 the sand hill region and east of it. This, together with the fact that none 

 of the few cottonwood and hackberry trees found growing within the 

 region are more than 25 years old, points either to destructive fires or to 

 an increasing aridity of climate as having been hostile to the occurrence 

 of trees. The scantness of the grass cover makes it improbable that 

 fire has been the deforesting factor, and the success of the planted trees 

 indicates that whatever features of the climate and soil are inimical to 

 spontaneous afforestation have to do with germination and the early 

 history of the seedling. 



