On the development of the pollen grain and anther 



of some Onagraceae. 



By 

 Rudolf Beer, 



Westwood, Bickley, Keiit (England). 



With 3 Plates. 



The striking character of the pollen grains of the Onagra- 

 ceae has attracted the attention of botanists from a very 

 early date. 



Already in 1830 Pui'kinje examined and figiu-ed the pollen of 

 several species („De cellulis Antheraiuni Fibrosis etc." Vratis- 

 laviae 1830) and since that time Hngo von Mo hl, Fritsche, 

 Schacht, Nägeli, Lnerssen, Tschistiakof f, Sachs, Wille 

 and Strasburger, as well as others have all paid greater or 

 less attention to this subject. By far the most detailed account 

 which we posses is that of Strasbnrger embodied in his two 

 memoirs upon the cell-waU (1. ,,Über den Bau und das AVachs- 

 tum der Zellhäute'- 1882, pp. 95— 100. 2. „Über das Wachstum 

 vegetabilischer Zellhäute'^ 1889, pp. 36— 46> 



In spite of this attention our knowledge of the development 

 of these anthers is still incomplete and it was the purpose of 

 the present research to re-examine the subject and, if possible, 

 to add a few details to the existing accounts. 



The species which have been examined are Oenotliera longi- 

 flora, 0. hiennis and Gaura Lindhehneri. Ey'dohmm tetragonum 

 and E. mo7itanum have also been examined but less thoroughly. 



The early development of the anther takes place in quite 

 the usual manner. A single longitudinal row of hypodermal 

 cells (the archesporium) divido into an inner series of primär}' 

 sporogenous cells and an outer row of primary parietal cells ^j. 



In the latter a succession of periclinal divisions follow one 

 another until, usually, four layers of cells separate the column 



1) The terminology used here in tliat given in Coulter aud Cliamber- 

 lains „Morphology of Angiosperms" 190.3. p. .33. 



