550 



SCIENCE. 



[N. S. Vol. XVII. No. 431. 



tricles of Mytilus, Mya, Haliotis, Lucapina, 

 Limax, Ariolimax, Octopus, and the decapods 

 examined, very much like the vagus inhibi- 

 tion in vertebrates. In Ariolimax and Mya 

 the inhibitory effect of single induced make 

 or break shocks is readily demonstrated. If 

 the application of a vceak, interrupted current 

 is long continued the ventricle will generally 

 ' escape ' from the inhibition during the stim- 

 ulation. Cessation of the stimulation is gen- 

 erally followed by acceleration in the rate and 

 increase in the magnitude of the beats. 



5. The direct current produces raake beats, 

 make and break beats, total diastolic inhibi- 

 tion, partial inhibition of beats, acceleration 

 of beats, and increase in ' tone ' or a continu- 

 ous ' tetanic ' contraction, according to its in- 

 tensity and direction, i. e., whether the anode 

 or the cathode is on the auricular end of the 

 ventricles. In Ariolimax this difference in 

 the ventricular response, according as the 

 anode or the cathode is on the auricular end, 

 is very manifest even with single induced 

 shocks. 



An account of previous investigations touch- 

 ing this subject is deferred to the more com- 

 plete statement which will accompany the 

 publication of the tracings. 



A. J. Carlson. 



Stanford University, 

 January 25, 1903. 



CURRENT NOTES ON PHYSIOGRAPHY. 



SOUTHERN APPALACHIAN EOREST RESERVE. 



' Senate Document 84 ' is a volume of 210 

 pages, 75 plates and 3 maps with the follow- 

 ing title : ' Message from the President of the 

 United States, transmitting a report of the 

 Secretary of Agriculture in relation to the 

 forests, rivers and mountains of the Southern 

 Appalachian region' (Washington, 1902). 

 ' Southern Appalachian Region ' is the page 

 heading throughout. The volume, whatever 

 its name may be, is worth owning, as it pre- 

 sents an unusually well-illustrated account of 

 ' the greatest physiographic feature in the 

 eastern half of the continent,' with special 

 reference to the creation by Congress of a 

 national forest reserve, for conservation of 

 the forest by use, rather than a national park. 



for conservation without use, as the Secretary 

 of Agriculture puts it (p. 167). Chapters on 

 topography and geology by Keith, hydrog- 

 raphy by Pressey and Myers, and climate by 

 Henry give concise accounts of these topics. 

 Many of the plates are excellent. The text 

 and the explanatory titles of some of the 

 plates give, to our reading, too much impor- 

 tance to forest clearing as a cause of de- 

 structive floods. There seems exaggeration 

 also in the statement under a fine view of 

 Stone mountain, near Atlanta, Ga. (PI. 

 XIX.), that 'the ax and fire have removed 

 the forest, and the heavy rains have removed 

 the soil which once covered the larger part of 

 this rocky knob.' It is estimated that not 

 less than 10 per cent, of the region has a 

 slope of less than ten degrees, while 24 per 

 cent, of the region has been cleared. The 

 hill- and mountain-side fields lose their surface 

 soil in five or ten years, and must then be 

 abandoned for new clearings. Native grasses 

 do not suffice to hold the hillside soils, which 

 are therefore often deeply gullied by rain 

 wash. It is evidently out of the question to 

 adopt the practice of terracing the hillsides, 

 as is done by the ~ crowded population of 

 eastern Asia (see a good illustration in 

 Geogr. Journ., XXL, 1903, p. 116). 



The Blue ridge, an important physiographic 

 element of the region, is variously described 

 in different parts of the volume; on one page 

 it is ' a fairly well-defined mountain range ' ; 

 on another, its northern part ' consists of 

 ancient plateaus' while upon ' the southern 

 part of the chain * * * are situated a few 

 individual peaks and ridges of commanding 

 height ' ; again, it is a ' steep and well-defined 

 escarpment,' and it fronts the Piedmont pla- 

 teau ' like a rampart.' The italics are here 

 introduced to emphasize the versatility of 

 this remarkable ridge. 



SOUTHERN PATAGONIA. 



Reference has already been made in these 

 notes to Hatcher's exploration in Patagonia. 

 Fuller description of his geographical results 

 has now been published (' Reports of the 

 Princeton University Expeditions to Pata- 



