146 



As regards phenological observations, I may mention that 

 Hartz found that, at Scoresby Sonnd, Diapensia opened -both 

 flowers and leaves -on June 12th; and Vanhoffen in 1893 found 

 that at Karajak (West Greenland) it opened on June 13th.^ 



According to my investigations, fertilisation and embryogeny 

 must certainly often take place long after pollination. 



The capsules may remain upon the plants far into the next 

 vegetative period. The seeds are probably scattered very slowly. 

 I have found a well-developed embryo in the latter. 



B. The Anatomy. 



W. Grevel has studied the anatomy of Diapensiaceae and 

 has given what appears to be a very thorough and exhaustive 

 description of the anatomical structure of Diapensia lapponica^ 

 except that of the root. For all details of a systematic-ana- 

 tomical nature the reader should refer to this paper, to which 

 1 can make but few additions ; my aim here is to direct atten- 

 tion to those features of its anatomy which are of especial 

 value to it in relation to climate and other external factors. 



The leaf. (Figs. 4 and 5). The epidermis of the upper and of 

 the lower surface is very much thickened, especially that of the 

 upper surface. A very thick cuticle occurs everywhere, but it is 

 thicker on the upper surface, and is there characterized by 

 not being of the same thickness everywhere; it sinks at times 

 into depressions of the cellulose membrane. The whole of the 

 external surface of the cuticle is wavy. In the outer walls the 

 layers beneath the cuticle (in both the upper and the lower 

 epidermis) are not quite evenly deposited; there occur, especi- 

 ally towards the lateral walls, canals which extend from the 

 interior outwards towards the cuticle, without, however, reaching 

 the latter. 



^ Cf. A. Cleve, 1901, p. 41. "Auf dem Plateau in Knospe und Blüte -^/e, 

 in voller Blüte, ausserdem mit Knospen und verblüht -^"/g; Kronenblätter 

 meist weg *It, Früchte aufgeschwollen noch nicht reif '''(9." 



