CHAP. I. HOTTONIA PALUSTRIS. 51 



purpose. The pistil of the long-styled form is more 

 than twice as long as that of the short-styled, with the 

 stigma rather smaller, though rougher. H. Miiller * 

 gives figures of the stigmatic papillae of the two forms, 

 and those of the long-styled are seen to be more than 

 double the length, and much thicker than the papillae 

 of the short-styled form. The anthers in the one form 

 do not stand exactly on a level with the stigma in 

 the other form; for the distance between the organs 

 is greater in the short-styled than in the long-styled 

 flowers in the proportion of 100 to 71. In dried speci- 

 mens soaked in water the anthers of the short-styled 

 form are larger than those of the long-styled, in the 

 ratio of 100 to 83. The pollen-grains, also, from the 

 short-styled flowers are conspicuously larger than those 

 from the long-styled; the ratio between the diameters 

 of the moistened grains being as 100 to 64, according 

 to my measurements, but according to the measure- 

 ments of H. Miiller as 100 to 61 ; and his are probably 

 the more accurate of the two. The contents of the 

 larger pollen-grains appear more coarsely granular 

 and of a browner tint, than those in the smaller 

 grains. The two forms of Hottonia thus agree closely 

 in most respects with those of the heterostyled species 

 of Primula. The flowers of Hottonia are cross-ferti- 

 lised, according to Miiller, chiefly by Diptera. 



Mr. Scott f made a few trials on a short-styled plant, 

 and found that the legitimate unions were in all ways 

 more fertile than the illegitimate; but since the pub- 

 lication of his paper H. Miiller has made much fuller 

 experiments, and I give his results in the follow- 

 ing table, drawn up in accordance with my usual 

 plan : 



*'Die Befruchtung,' &c., page t 'Journ. Linn. Soc. Bot.,' vol. 

 350. viii., 1864, p. 79. 



