THE POLLEN-GRAINS 347 



that if these observations be confirmed by more detailed investiga- 

 tions the view I have elsewhere advanced of Sea Island being 

 a hybrid between G. vitifolium (or perhaps even still earlier, 

 G. punctatum) and G. brasiliense may be universally accepted (see 

 pp. 305-6). 



In making these observations on pollen-grains I have perhaps y a j ue o 

 gone as far as my studies warrant at present. I am, however, con- pollen- 

 strained to believe that botanists may have erred, by going to the 

 opposite extreme : namely, in believing that the characters of the 

 pollen-grains are invariably generic, if not ordinal in value, and 

 cannot therefore be utilised in separating species, if not groups of 

 species, within certain genera. 



The following explanatory notes on the two plates here given to 

 exemplify the pollen-grains seen in Gossypium may be helpful, 

 though I again desire to repeat that it is not intended these illustra- 

 tions should be regarded as more than suggestive of further 

 inquiry : 



PLATE No. 52. 



Fig. 1. Shows the pollen-grain of G. drynarioides magnified 450 

 diameters. It, as also all the others given, can therefore be readily 

 measured for actual size. (Cf. p. 71.) 



Fig. 2. The pollen-grain seen in G. Sturtiix&SQ (p. 63). 



Fig. 3. The pollen-grain of G. Darwiniix&5(j (p. 68). 



Fig. 4. The grain seen in G. Stocksii x 450 (p. 73). 



Figs. 5 and 6. Two forms of grain met with in the Molango state 

 of Upland Cotton (G. hirsutumxmexicanum) x450 (p. 231). 



Fig. 7. The pollen-grain seen in G. arboreum x 300 (p. 81). 



Fig. 8. The form characteristic of G. obtusifolium (wild state) 

 x 300 (p. 139). 



Figs. 9 and 10. Spores seen in G. obtusifolium, var. africana, x 300 

 (p. 153). The former belongs to the G. obtusifolium type and the 

 latter to the G. arboreum x 300. 



PLATE No. 53. 



Fig. 11. The spore most abundant in G. barbadense, var. maritima 

 (Sea Island cotton), x 450 (cf. p. 275). Its associated spore is 

 identical with that shown on f. 18. 



Fig. 12. The spore that seems to be characteristic of roji cotton 

 x450, and looks as if it might be spoken of as a Mosaic hybrid 

 spore (p. 134). 



