HITCHCOCK: A PECULIAR SPBCIES OF LASIACIS 



35 



cm'./g., anddP/dr is the slope of the P — T curve expressed 

 in megabars per degree; practically it is the pressure in megabars 

 required to raise the melting point one degree. Over the range 

 of temperature covered by our measurements we find 



A H = 25 cal. per gram. 



This is a value which is higher than the latent heat of melting 



TABLE 2 

 ResuivTS for Freezing Pressures, and Change op Volume of Freezing 



" By extrapolation. 



of most substances. On the other hand the compressibility and 

 change of volume upon freezing do not differ markedly from the 

 average for organic liquids. 



BOTANY. — A peculiar species of Lasiacis. A. S. Hitchcock, 

 Bureau of Plant Industry. 



In 1759 Linnaeus described Panicum divaricatum^ from 

 Jamaica, distinguishing the species as divaricately much- 

 branched. This is the first species to be described of a group 

 having perennial branched, woody clambering or trailing stems, 

 broad, flat blades, and panicles of smooth, roundish spikelets, set 

 obhquely on the pedicels, the indurate fruit with a woolly tip. 

 The aspect of the plants is that of a shrubby climbing bamboo. 

 Several allied species have been described and referred to the 

 genus Panicum. In 1864 Grisebach- recognized the group as a 



1 Syst. Nat. ed. 10. 2: 871. 1759. 



2 Fl. Brit. W. Ind. 551. 1864. 



