115 
rounded cells without intercellular spaces. In the innermost 
layer isolated bast-cells occur. The secondary cortex, which 
according to SEGERSTEDT is produced on branches 3—5 years of 
age, does not renew the epidermis as is the case in Arct. 
alpina. There are typical annual rings, and the spring and 
summer wood are distinctly differentiated. Now and then a 
tendency may be traced towards the formation of irregular, ill- 
defined annual rings, a fact which is often met with in the 
other Ericacew, Rhodoraceæ and Vaccinaceæ treated in the 
present paper. 
In the root I have not observed endotrophic hyphe (ef. 
HesseLman). 
Except the difference in regard to the palisade-cells I am 
not aware of having observed any other points in which the 
specimens from other countries differed from the Danish in- 
dividuals. 
Arctostaphylos alpina (L.) Spreng. (Fig. 28.) 
BôrGEsEN, 1895, pp. 236—237. O. G. Petersen, 1901, p. 75. 
Amprony, 1890, p. 70. 
I have had specimens for investigation from the following 
localities: — East Greenland: Hekla Havn (N. Hartz); Danmarks O 
(April 10, 1892, N. Hartz). Norway: (Finmark) Tromsö at Flöj- 
fjæld (July 24 and 27, 1885, E. W. Sweden: Jämtland (July, 
E. W.). Denmark: diff. localities. 
The leaf being deciduous, it naturally differs somewhat 
in structure from that of the previous plant. Structures which 
tend to check excessive transpiration and which are especi- 
ally necessary to protect plants against the dryness of the 
winter's cold, do not occur. The present species differs from 
the above in regard to the assimilatory tissue also, which 
is in itself peculiar as evergreen leaves do not assimilate very 
much during winter; in short we are here dealing with quite 
a different type. 
ee 
