Beer, Development of the pollen grain and anther of some Onagraceae. -87 
of primary sporogenous eells from tlie epidermis. The outer- 
most parietal layer is the endothecium or fibrous layer; within 
tliis follow (usually) two „middle layers" and finally, adjoining 
the sporogenous tissue, the tapetum becomes differentiated. 
As is well known tlie primary sporogenous cells of Goura 
form a single longitudinal row. Subsequently certain of these 
sporogenous cells become „sterile“ and, by their division, form 
transverse septa, liere and there, across the anther. The forma- 
tion of these septa in certain members of the Onagraceae has 
already been described by Barcianu (Inaug.-Diss. Leipzig 1874 
„Unters, über d. Blüt e n ent wie B. d. Onagraceae" p. 21) and by 
Bo wer (Studies in the Morphology of spore-producing members. 
II. Ophioglossaceae 1896, p. 1). 
Large raphide-sacs occur in the connective of all the species 
examined. The bündle of crvstals of eacli sac is enveloped in 
a mucilage which stains violet with a mixture of methylene 
blue and fuchsin and pink witli rutherium red. These reactions 
indicate a pectic body. The crystals and their mucilage slieath 
do not tili the entire sac but the space which is left between 
them and the wall of the sac is occupied by a material which 
has often a reticulate structure. In Heidenhain s Iron-haema- 
toxylin the mucilage slieath becomes black wliilst the reticular 
Investment remains uncoloured (Big. 14). Xo starch and no 
plastids were ever seen in the sacs which enclose raphides. "W ar- 
ming in his description of the anther of Epilobium angustifolium 
(Unters, über pollenbildende Pliyllome und Kaulome. Bonn 1873. 
p. 23) calls attention to certain large, ellipsoidal cells which lie 
in the connective but the nature of which he left midetermined. 
These cells are the rapliide-containing sacs mentioned above 
which reacli quite a remarkable development in tlie species of 
Epilobium. 
In Oenothera biennis and 0. longiflora tannin also occurs in 
the anther, both in the epidermis and in a varying number of 
cells of the connective. On eacli side of the anther, along the 
line of future dehiscence, a longitudinal band of epidermal cells 
always remains free from tannin. The cells of these two lateral, 
tannin-free bands soon ceases to grow and become stretched 
and flattened by tlie enlargement of the anther. Beneath each 
of these two lines of peculiar epidermal cells a longitudinal air- 
passage is fornied at a very early stage 1 ). This passage arises, 
in the first place, by a Separation of cells from one another at these 
spots but subsequently the cavity is enlarged by the cells bor- 
dering upon the space becoming flattened and destroyed by the 
growth of the anther. 
In some anthers a curious development of the cell-walls 
bordering upon the air-passage was observed. The cell-walls in 
question become greatly thickened and cuticularised in a manner 
1 ) Some time before the appearance of the callose motlier-cell walls. 
