2 POLLEN. 



going through all the natural families in detail, with 

 numerous plates drawn to scale, and published in 

 the 'Annals of Nat. Hist.' 1842, vol. viii. ix. 



6. Lindley published figures of pollen after some of the 



above authors ; and 



7. A further republication of them in the ' Micrographical 



Dictionary.' 



8. Since that time Herman Schacht has published some 



beautiful drawings in the ' Jahrbuch der Botanik,' 

 Berlin, 1860, ii. p. 109. I agree very much with 

 what he has published, except about the Pinus 

 family, of which his descriptions differ from what I 

 have observed, and from the drawings of Mohl, and 

 Hassall, and Dr. Hooker. 



9. Nagilihas also a paper in the same publication, vol. iii. 



Eosanoff has a paper in the same publication (1865), 

 vii. p. 34, principally on the pollen of the Acacise. 



10. Leursen, in vol. vii. p. 34 of the same publication, 

 reviews a paper by 



11. M. Pollenden, Bonn, 1867; 



12. A paper by Mr. A. W. Bennett in the 'Popular 



Science Eeview,' April, 1875 ; and lastly, 



13. Some woodcuts by Mr. Worthington Smith in the 

 * Gardener's Chronicle ' in October last ; republished 

 in the 'Microscopical Journal,' January, 1877. 



The pollen forms are often noticed by Dr. Hooker in his 

 large works, and also by some foreign botanists in the 

 Brazil Flora. 



It is remarkable, that while in some families the species 

 vary greatly, in others they are almost always the same. 

 Some may therefore be considered normal ; others as having 

 only a specific value. The different size of the grains is 

 also marvellous : some very large, and visible to the naked 

 eye, as in Stachytarpheta, the Malvacese, Cobsea, Pan- 

 cratium, and some species of Iris, reaching as much as -^ th 

 of an inch; while others, as many Boraginese, Primulaceae, Me- 

 lastomacese, and Saxifragese, are as small as | 00 ths of an 

 inch. In colour also they are very various, but usually some 

 shade of yellow or white; but I have observed blue, red, 

 brown, or rarely green, which has been denied by Lindley. 



