516 Biologie. — Morphologie, Befruchtung, etc. 



structure and biology of arctic flowering plants. I. Erici- 

 neae, 1. Morphology and Biology). (Meddelelser om Grönland. 

 36. Copenhagen 1908. PI. 1—71. 44 figures.) 



The present paper is the first of a series of papers on Arctic 

 flowering plants, which will probably be published. 



The morphology and biology of the foUowing plants is described 

 and illustrated by numerous figures: Andromeda polifolia, Arctosta- 

 phylos alpina, A. Uva-iirsi, Cassiope hypnoides, C. ietragona, Leduni 

 paltistre, Loiseleuria procuntbens, Lyonia calyciilata, Phyllodoce coe- 

 rulea, Pirola minor, P. ttnißora, P. rottindifolia , P. secunda, Rhodo- 

 dendron lapponicum , Vaccinium Myrtillus, V. Occycoccos, V. uliginosum, 

 V. Vitis-idaea. 



From the summary of results we may take the following: All 

 species are adapted for cross-pollination by insects, and all, except 

 Pirola, secrete honey. The pollen grains are glabrous and dry. 

 With some exceptions all the species which have bell-shaped and 

 drooping flowers, bear appendages upon the anthers. The usefulnes 

 thereof is that visiting insects will touch them and thereby shake 

 the pollen out of the anthers. On the other band, the appendages 

 are wanting in species with open and not drooping flowers. 



In most cases, self-pollination will be able to take place easily, 

 and in some arctic species there occurs even a tendency to facililate 

 it, which can be connected with the scarcity of insects in the arctic 

 countries. In some species a kind of cleistogamy seems to occur, 

 the anthers opening while still in the bud. 



All the Greenland Ericaceae have woody stems and should be 

 referred to the growth-form called dwarf-shrubs. Only two species 

 out of 16 have typical deciduous leaves, the leaves of 13 species 

 keeping fresh through at least one winter. The leaves of Arctosta- 

 phylos alpina appear neither to fall nor to keep fresh during winter. 



Ove Paulsen. 



Gebbs, L. S., Notes on the Development and Structure of 

 the seed in the Alsinioideae . (Annais of Botany. Vol. XXI. p. 

 25—55. With two plates. 1907.) 



A considerable number of species was examined and the struc- 

 ture was found to be very uniform. Stellaria media was studied as 

 far as the maturation of the seed and Cerastium perfoliatum for 

 the germination. A füll account of former work on the group 

 is given. 



In Stellaria media the ovules arise in basipetal succession ori 

 the columella before the latter is closed in by the carpels. The pri- 

 mary megaspore arises as a large hj'^podermal cell and becomes the 

 functional megaspore without division; its growth takes place at the 

 expense of the cells below it in the same vertical row. The two in- 

 teguments arise in basipetal succession. The development of the 

 embryosac is normal. The cells of the nucellus undergo rapid di- 

 vision and those just under the micropyle are prolonged into papillae. 

 Digestion of the nucellus surrounding the embr3^osac takes place, 

 the actual cytoplasm of the sac probably being the active agent. 

 Fusion of the polar nuclei goes on and this is followed by a 

 long rest. 



The pollen tubes, after growing along the papillate cells of the 

 Stigma, pass down the style, and penetrate the septa of the ovary; 

 the latter are spongy in structure and are covered with papillae. 



