Notes on Pollen. By Worthington G. Smith. 9 
studied as transparent objects, provided a strong light and a good 
condenser were used, 
4 inches 
Fig. 2 represents the entire instrument, which is made by Mr. 
Hawkesley, of Oxford Street. 
III.—WNotes on Pollen. By Worruineron G. Surru, F.LS. 
Puates CLXVIL., CLXVIIL., CLXIX., anp CLXX. 
THE following notes on pollen have reference alone to the external 
form of a few typical pollen-grains as seen under the microscope. 
The formation of pollen within the mother-cells, the minute ana- 
tomical structure of pollen, and the nature of the pollen-tube, will 
not here be touched upon. A few words may be written on these 
latter subjects on another occasion. 
The accompanying illustrations are all engraved direct from 
nature to one uniform scale; all the figures are enlarged 400 
diameters. A mere glance will show how extremely pollen-grains 
differ in size, in form, and in external marking: they also differ 
greatly in colour, but from necessity on this occasion the colours 
cannot be conveniently reproduced. In nearly every instance the 
peculiar markings or reticulations on the cells are only partly indi- 
cated in these engravings (to save labour) : for instance, in Fig. 5 the 
pattern is complete, whereas in 13 and 14 the peculiar markings are 
left unfinished for the reason mentioned. Pollen-grains also differ 
very much from each other in their viscidity or dryness of surface, 
and in their density or translucency. As a rule, pollen-grains are 
