466 BOTANICAL GAZETTE [decembek 



has been studying Cyclamen. Among his important results, we may note 

 that the place at which regeneration occurs may be altered by putting a 

 plaster of Paris cap over the cut end of the petiole. A similar cap or a coat 

 of shellac over the leaf causes regeneration without cutting. — S, Prowazek 

 (Biol. Centralbl. 21:87-95, 144-155. 1901) and O. Hubner (Zool. Jahrb. 

 15:461-498. IQ02) have studied regeneration, chiefly in animals, though 

 working on a few plant forms. Hubner adheres to Weismann*s adaptation 

 theory and thinks that the capacity for regeneration has been developed by 

 natural selection. — H. C. Cowles. 



Some recent bulletins of the United States Bureau of Forestry add to 

 the knowledge of the silvicultural (ecological) behavior of certain trees. 

 Olmsted's discusses the relation of three forest societies in Arkansas. The 

 "pine ridges" are the most xerophytic. More than 50 per cent, of the ridges 

 have pine, 38 per cent, being short-leaf pine {^Pinns echtnata Mull.) and 16 

 per cent, loblolly pine (/*/;z//j /tz^^/^ Linn.). The remaining portion comprises 

 oaks and other deciduous trees. Seedhngs of the pines mentioned are found 

 not to be tolerant of shade. In more mesophytic conditions, on the "pine 

 flats,*' t^e loblolly pine comprises 34 per cent, of the growth, and the short- 

 leaf pine only 20 per cent., the remaining being deciduous trees. In the 

 hydro-mesophytic conditions along streams, the so-called "hardwood bot- 

 toms," the pines are entirely absent. This is due to the fact that these lands 

 are frequently flooded, also the ground is too heavily forested for the germi- 

 nation of pine seedlings. The author gives silvicultural notes on the most 

 important species, and in part two discusses the management of the forest. 



In another bulletin Allen '^ shows that the western hemlock {Tsuga hete- 

 rophylla Sargent) requires a climate with a heavy rainfall, and that it is 

 exceedingly tolerant of shade. This latter characteristic is of very great 

 importance in determining the composition of the forest in which it grows. 

 The author also gives an excellent report of the insects that infest the tree, 

 and emphasizes the fact that its usefulness as a lumber, tanning, and paper 

 pulp tree has been greatly underestimated. — H. N. Whitford. 



'5 Olmsted, F. E., A working plan for forest lands near Pine bluff, Arkansas. 

 Bureau For. U, S. Dept. Agric. Bull. 32. pp. 48. //j, //. figs. 9. 1902. 



. *^ Allen, E. T., The western hemlock. Bureau For. U. S. Dept. Agric. Bull. 33- 

 PP- 55- P^s* ^2. 1902. 



