348 



WILD AND CULTIVATED COTTONS 



Biblio- 

 graphy. 



Schacht. 



Figs. 13, 14, and 15. Three conditions of pollen-grains found in an 

 artificially produced hybrid made by Professor Gammie at Poona 

 goghari x varadi x 450 (pp. 111-2, 134). The first (13) closely matches 

 No. 6, one of the spores of Molango cotton ; 14 brings to mind the 

 grain seen in many forms of G. Nanking ; while 15 matches f. 9, seen 

 in G. obtusifolium in Africa and also f. 8, G. obtusifolium, the wild 

 state found in Kathiawar. 



Fig. 16 is the spore found in G. punctatum, var, Jamaica, x 300 

 (p. 170). 



Fig. 17. The pollen-grains of G. PalmeriixSQQ (p. 204). This 

 spore is seen in many of the Upland cottons such as ff. 6, 13. 



Fig. 18. This shows the pollen-grain found in all the wild or 

 acclimatised forms of G. brasiliense x 450 (p. 295). It is also the 

 alternative grain met with in the Sea Islands, Peruvian, &c. 



Fig. 19. The spore most general in G. taiteme, was taken from 

 Deplanche's specimen n. 417 (p. 248). 



Fig. 20. The spore of G. peruvianum, taken from G. F. im 

 Thurn's n. 79 (pp. 213, 216). The alternative grain being f. 18. 



Fig. 21. The pollen-grain of G. Kirkii, a somewhat remarkable 

 form with long sharp spines deflected to one side (p. 316). 



Bibliography of Pollen-grains in Malvacea. It may be useful to 

 bring together in this place a few passages from authors who have 

 described the pollen-grains seen in MALVACEAE, more especially 

 Gossypium. While doing so it may be possible to exhibit opinions 

 that have a bearing on the suggestions advanced by me regarding 

 pollination and hybridisation. 



1. Hermann Schacht (in Pringheirn's 'Jahrbucher fur wissensch. Bot.' 

 1860, n., 109-68, xiv.-xvin.) gave considerable attention to the subject 

 of pollen-grains, and was, perhaps, one of the earliest investigators to 

 figure and describe one of the forms met with in Gossypium. His 

 picture exhibits what he calls the pollen of G. religiosum. Schacht's 

 method of staining with dilute sulphuric acid, gives a somewhat striking 

 result, as it colours the outer coat of the grain (the exine) a bright red tint 

 but imparts to the surface of the grain a blue line, due, he believes, to the 

 diffusion of oil over the surface of the grain. Schacht uses the expression 

 of the exine being like a palisade structure, an admirable description, but 

 he shows it as possessing in addition a few hyaline spines that do not 

 arise from warts. A protuberance of the intine and cell-contents is shown 

 to press against the exine, causing it to become thin and finally to rupture. 

 No specially constructed pores are, however, indicated, though numerous 

 perforations and thinning portions are shown. The condition indicated 

 much resembles that in Plate 52, ff. 1 & 5, also 53, f. 13. 



The thickening of the intine, and the thinning of the exine, is 



