On the development of the pollen grain and anther 
of some Onagraceae. 
By 
Rudolf Beer, 
Westwood, Bickley, Keilt (England). 
Witli 3 Plates. 
The strikiifg character of the pollen grains of the Onagra¬ 
ceae has attracted the attention of botanists from a very 
early date. 
Already in 1830 Purkinje examined and ügured tlie pollen of 
several species („De cellulis Antherarum Fibrosis etc." 1 ratis- 
laviae 1830) alid since that time Hugo von Mo hl, F ritsche, 
Schacht, Hägeli, Luerssen, Tschistiakoff, Sachs, Wille 
and Strasburger, as well as others jjjave all paid great er or 
less attention to this subject. By far the most detailed account 
which we posses is that of Strasburger embodied in his two 
memoirs npon the cell-wall (1. „Über den Bau und das Wachs¬ 
tum der Zellhäute“ 1882, pp. 95—100. 2. „Über das Wachstum 
vegetabilischer Zellhäute“ 1889, pp. 36—46). - , 
In spite of tliis attention our knowledge of the development 
of fliese 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 Oenothera longi- 
fiora, 0. biennis and Gaura Lindheimeri. Epilobium tetragonum 
and E. montanum have also been examined but less thoroughly. 
The early development of the anther takes place in cpiite 
the usual manner. A single longitudinal row of hypodermal 
cells (the archesporium) divide into an inner series of priuiary 
sporogenous cells and an outer row of primary parietal cellsb. 
In the latter a succession of periclinal divisions follow one 
another until, usually, four layers of cells separate the column 
i) The terminology used liere in tkat given in Coulter and Clianiber- 
lains „Morpliology of Angiosperms“ 1903. p. 33. 
