iQoS] CURRENT LITERATURE 7^ 



Seed dispersal in Polygonum. — 



'ffltWIH 



virgmianim has a somewhat unique means of seed dispersal. When an object 

 hits the rigid persistent style, the akene is violently ejected. It is found that a 



arises 



pedicel through the growth of the pith below the separation layer. This growth 

 is sufficient to cause the compression of the pith above the layer, since the bounding 

 vascular cells are rigid. The release of these cells from this pressure, when the 

 atene is detached by a stroke, causes the shooting of the akenes to a distance of 

 three or four meters. — H. C. Cowtes. 



Solution tension and lipolysis.— Pond^' has investigated the effect of various 

 toxic salts upon the saponification of ethyl butyrate by a commercial product, 

 holadin. Whereas Mathews, McGuig.^x, and Caldwell concluded from their 

 results with eggs of Fundulus, diastatic digestion, and proteolysis, respecUvely, 

 that toxicity was an inverse function of solution tension, Pond concludes that m 

 lipolysis this is not true of the salts tested. He points out also various discrej^cies 

 in the results of these investigator, emphasizing the want of agreement and the 

 extent of the divergence of obser\-ed from calculated values.— C. R. B. 



Swiss vegetation.-Few countries are better knoum phjtogeographicaUy than 

 Switzerland. Grisch^^ j^^s given a detailed account of one of the less known dis- 

 tricts. The entire area studied contains only subalpine, alpine, or nival ye^tauon. 

 Much is made of the influence of snow, and it is pointed out that snow is as detri- 

 mental to some plants as it is favorable to others. This was brought out by 

 some interesting experiments that supplemented the field study. A detailed treat- 

 ment of the various plant formations, and an annotated list of the species make up 

 the body of the paper.— H. C. Cowles. 



Heliotropism in a lichen.-XEMEC has tested experimentally an inference of 

 Sachs from observations in nature that the thallus of Peitigera camna reacted to 

 Ught like the thallus of Marchantia.- He finds Peitigera aphihosa d^tmctly helio- 

 tropic, without having the rate of this reaction influenced by geotropism, and mm 

 a non-rever.ible inherent doisiventrulity. The young rhizines are negatively 

 heliotropic. The perceptive and active regions have not been detennmed. C K.is. 



~ .6 R^E^, H. S-, and SMOor, L, The mechanism of seed-dispersai in Polygonum 



vkginianum. Bull. Torr. Bot. Club 33 '•377'3^- ^9°^' 



n PaxD, R. H-, Solution tension and toxicity in Upob-sis. Am. Jour. Phv-s. ig. 



25^^-283. 190 



- .__, Andr., Beitrage zur Kenntnbs der pflanzengeographischen 

 nisae der Bergunei^tocke. Beih. Bot. Centralbl. 22-255-3^6. 1907- 



^. Xemkc, B., Die heliotropische Orientation des Thallus von Pe^g^ 

 <L.) Hofltm. Bull. Int. Acad. Sci. Bohame 1 1 : i-5- ^9^- 



