Caryophyllaceæ. 269 



experimental investigations of Lathy rus maritimus (Bot. 

 Tidsskrift, Köbenhavn, 1899, p. 22). 



The different points of information concerning the 

 leaf-anatomy of Alpine plants, may profitably be compared 

 with those concerning that of the Arctic leaves. Schröder, 

 in his excellent work "Das Pflanzenleben der Alpen", 

 mentions the first-named and gives a resumé of Bonnier's 

 and Wagner's results, which, in certain directions, show 

 deviations from the Arctic species, especially as regards the 

 palisade-tissue. When the Arctic plants have, on the whole, 

 less differentiated palisade-tissue than the Alpine species, 

 this must be especially attributed to the fainter light and 

 the fogs in Arctic countries. 



The fact that the mesophyll in Arctic plants is always 

 thin-walled, and has abundant intercellular spaces, has been 

 emphazied by previous authors, for instance Börgesen and 

 Th. Holm; and is evident from numerous figures which a 

 number of authors have published in the "Morphology and 

 Biology of Arctic Plants", "Meddelelser om Grönland", 

 Vols. 36 and 37 (for instance O. Gallöe, 1910; Knud Jessen, 

 1911 and 1913; Carsten Olsen, 1914; Mathiesen, 1916; 

 H. E. Petersen, 1908, and others). In this, according to 

 Wagner, there is a conformity with the Alpine species, a con- 

 formity which must be attributed to the greater moisture 1 . 



In Cerastium arvense (from willow copses in Kangard- 

 luarsuk in West Greenland) the spongy tissue was of an 

 unusual character, consisting more or less of stellately branch- 

 ed cells, for which reason the lacunæ were particularly large. 

 There was a distinct palisade-tissue with at least 3 cells in a 

 vertical row. The epidermal cells had undulating walls and 

 stomata on both surfaces. 



1 For purposes of comparison see the anatomy of woody plants 

 in Warming (1887), H. E. Petfrsen (1908), and Mentz (1909). 



XXXVII. 18 



