swingle: seyerixia euxifolia 651 



junctions of two Le Chatelier thermocouples within a furnace 60 

 cm. long, several series of accurate observations in vacuo of the 

 thermoelectric power of the couple iron-platinum have been 

 taken, at 2° intervals, over the temperature range 0° to 1000°C. 



In the thermoelectric power vs. temperature curve the critical 

 point A 3 is marked by a discontinuity of considerable magnitude 

 at about 915°C. on heating, and at 900 C C. on cooling. At A 2 

 there is a change in shape of the curve. The thermal effect at 

 A 2 is superimposed upon the thermoelectric and manifests itself 

 as a slight protuberance or dent at 768°C. 



In Table 1 are given the thermoelectric power (dE di), Peltier 

 effect (TdE di), and Thomson Effect (d 2 E dt-) for iron-platinum 

 from 0° to 1000°C. 



These thermoelectric observations give further evidence of 

 the distinct character of the critical points A 2 and A 3 delimiting 

 the regions of alpha, beta, and gamma iron. 



BOTANY. — Severinia buxifolia, a Citrus relative native to southern 

 China. Walter T. Swingle. Bureau of Plant Industry. 



In southern China, Tonkin, and Annam, and in the adjacent 

 islands of Formosa. Hongkong, and Hainan, there occurs not 

 uncommonly a much-branched thorny shrub which has shiny 

 box-like leaves aDd small, black, berry-like fruits. 1-1.5 cm. in 

 diameter. This plant is commonly called Atalantia bilocularis 

 (Roxb.) Wall., or Atalantia buxifolia (Benth.) Oliv. in recent bo- 

 tanical works. In connection with a survey of the plants re- 

 lated to Citrus this plant has been studied, with the result that 

 it seems necessary to recognize it as constituting the type of a 

 distinct genus, for which, fortunately, there is a valid name. 

 Severinia. established in 1S40 by Tenore. 



The nomenclatorial history of this plant has been a checkered 

 one. The earliest reference to it by a European botanist seems 

 to have been in 1757. when Osbeck. one of Linnaeus 's pupils, 

 published the original Swedish edition of his diary of a voyage 

 to the East Indies. On October 20. 1751. he found on Danish 

 Island, near Canton. China, a plant of which he says "Buxoides 

 aculeata. what the Chinese call Sau-pann-gipp. is like our box- 



