212 
Beer. — Studies in Spore Development . 
rod lets vary in size, and are usually drumstick-shaped with a part of their 
knobs just projecting through the perforations of the outer lamella of the 
exine. The spines are now large (12-14 /x) spindle-shaped structures with 
the two prongs of their roots lying beneath the outer lamella of the exine 
and just reaching to the e mesospore *, and their apices passing through the 
outer lamella to the exterior. Between the rodlets and spine roots a homo- 
geneous, stainable material occurs ; this material is not protoplasmic in 
nature as it does not give the reactions characteristic of this substance 
(e. g. no xanthoproteic reaction). 
14. The tapetal cells do not disintegrate, and must, therefore, be 
classed with Goebel’s ‘ secretion-tapeta \ 
15. Deeply staining fibres and granules occur in the cytoplasm of the 
tapetal cells during the middle periods of anther development. 
1 6. Almost the entire growth of the rodlets and spines takes place 
after these have become separated from direct contact with the protoplast 
by the interpolation of the thickening bands (mesospore). Neither are they 
in contact with the tapetal or any other cytoplasm. The conclusion may, 
therefore, be drawn that these structures possess a certain power of growth 
independent of any direct protoplasmic influence, and, moreover, during 
this growth they are able to maintain their characteristic form. The growth 
of the spines and rodlets of Ipomoea appears, therefore, to be of quite the 
same character as that of the entire membranes of Isoetes , Selagindla , 
Oenothera , or Mirabilis. 
References to Literature. 
X. Beer, Rudolf : On the Development of the Pollen Grain and Anther of some Onagraceae. 
Beih. z. Bot. Centralbl., Bd. xix, Abt. i, Heft 2, 1905, pp. 286-313. 
2 . Campbell, D. H. : Studies on the Gametophyte of Selaginella. Ann. of Bot., vol. xvi, Sept., 
1902, pp. 419-428. 
3. Cavara, F. : Breve contribuzione alia conoscenza del nucleolo. Bull, della Soc. bot. ital., 
1902, p. 108. 
4. Denke, P. : Sporenentwickelung bei Selaginella. Beih. z. Bot. Centralbl., Bd. xii, Heft 2, 
1902, p. 182. 
5. Fitting, H. : Bau und Entwickelungsgeschichte der Makrosporen von Isoetes und Selaginella 9 
etc. Bot. Zeit., Bd. lviii, 1900, pp. 107-164. 
6. : Bot. Zeit., Bd. lxiv, 2. Abt., 1906, p. 42. 
7. : Bot. Zeit., Bd. lxiv, 2. Abt., 1906, p. 279. 
8. Goebel, K. : Organography of Plants, Part II, Oxford, 1905, p. 596. 
9 . Heidenhain, M. : Most recently in ‘Plasma und Zelle 1. Abt., 1. Lieferung, Jena, 1907, 
p. 179. There see earlier references. 
