318 Scientific Intelligence. 



ble life, and this is shown even in this part, which is devoted to 

 the appropriation and distribution of matters by plants. The 

 remaining volume, to be devoted to the relations of plants to the 

 forces, will possess even a higher degree of interest than the pres- 

 ent. We trust that Professor Pfeffer will give his consent to the 

 translation into English of this second edition of his valuable hand- 

 book, in order that it may reach a wider circle of thoughtful men 

 in many departments of thought. G. l. g. 



2. Permeability of the bark of tree-trunks to atmospheric gases. 

 — M. Henri Devaux, Comptes Rend., Dec. 6, 1897, has made use 

 of a simple apparatus for determining some of the relations of the 

 living peripheral layer in the trunks of large trees to the gases of 

 the atmosphere. He cements, by means of wax, a small funnel to 

 the bark of the tree to be examined, fills the funnel with water, 

 and then diminishing the pressure, observes the bubbles which 

 escape into the water. Apertures on large trunks are virtually 

 lenticels like those of small branches, and from these trunk lenti- 

 cels air escapes abundantly under the conditions noted. In some 

 cases there is a marked difference between the two sorts of lenti- 

 cels, those of the trunk being less permeable than those of the 

 twigs. 



Not only do respiratory exchanges take place through these 

 apertures but through accidental wounds, however small. In two 

 instances the impermeability of the lenticels was practically com- 

 plete, namely, in Picea excelsa and Populus alba. Even under 

 great exhaust no bubbles were withdrawn from the bark of these. 

 The experiments were conducted in October. Perhaps a different 

 condition of affairs as to permeability prevails at other seasons of 

 the year. 



One of the most interesting observations made by the investi- 

 gator was in regard to the influence exerted by lichens in occlud- 

 ing the lenticels. Even when the lichen on the trunk is crustace- 

 ous, and closely appressed, it does not close the pathway of the 

 gases to arid fro. No report is yet given as to the character of 

 the gases thus withdrawn from the plants. 



Two gaps appear to be unfilled in this account of the permea- 

 bility of the bark of tree-trunks : the recorder does not make it 

 clear that he eliminated errors arising from the contained air of 

 the corky layer; and, secondly, no proof appears that the gas 

 escaping in bubbles came wholly from the living tissues within 

 the corky layer. Nevertheless this application of an old method 

 is interesting and may suggest further steps in the same direction. 



G. L. G. 



3. Lessons with Plants : Suggestions for Seeing and Interpret- 

 ing some of the Common Forms of Vegetation; by L. H. Bailey. 

 Pp. xxxi + 491, figs. 446. New York, 1898 (The Macmillan 

 Company ; $1.10). — The purpose of Professor Bailey's book is not 

 to teach the science of botany but to serve as a guide in the 

 " nature-study " of plants, and it is intended for the use of 

 beginners in the secondary schools. In each chapter some 



