Studies in Spore Development. 
BY 
RUDOLF BEER, B.Sc., F.L.S. 
With Plate XIII. 
Introduction. 
D URING the eighties of last century great activity was displayed in 
the Investigation of the structure and development of the spores and 
pollen-grains of a large number of plants. The first impetus to this 
activity was due to the splendid investigations of Strasburger upon this 
subject, which he published in his treatise ‘ Ueber den Ban und das 
Wachsthum der Zellhaute ’ in 1882 (16). Two years later Hubert Leitgeb 
issued his studies upon the structure and development of a number of 
spores with particular reference to those of the Hepaticae. In 1886 
appeared Wille’s c Ueber die Entwickelungsgeschichte der Pollenkorner 
der Angiospermen whilst in 1889 Strasburger published a further series 
of studies on spores and pollen-grains in Heft II of his ‘ Histologische 
Beitrage 
After this date there was a temporary lull in the investigation of 
spore histology, and until the opening year of the new century the only 
important contribution to the subject — apart from the interesting micro- 
chemical work of Mangin— is yet another publication of Strasburger’s in 
1898 upon ‘ Die pflanzlichen Zellhaute ’ (18). 
In 1900 an important account of the structure and development of 
the spores of Isoetes and Selaginella appeared from the pen of Hans 
Fitting (5). In this work, crowded with a wealth of interesting details, 
probably the most unexpected feature was the demonstration that the 
spore-walls could carry on their growth although the protoplast of the 
spores was not in contact with them during this process. Fitting’s dis- 
covery was very soon confirmed in Selaginella by Campbell (2), and 
a little later by Denke (4). Miss Lyon (10 a) has given a different in- 
terpretation of the growth of these membranes, but I think her objec- 
tions have been sufficiently met by Fitting’s reply in the ‘ Botanlsche 
Zeitung ’ (6). In 1905 I was able to find another case ( Oenothera ) in 
which the pollen-membranes possess independent powers of growth 
[Annals of Botany, Vol. XXV. No. XCVII. January, igii.j 
