of the Presence of Iron in C/iromatin. 285 



cells of pollen sacs of Hyacinthus, all fixed in alcohol, give, with 

 several days' application of warm ammonium sulphide, under the 

 cover-glass, a greenish-blue or a dark green reaction. 



We have observed that the chromatin of the karyokinetic figures 

 in the pollen grains of Cucurbita shows an intense coloration with 

 ammonium sulphide. It has, moreover, been found that there is here, 

 as shown by the application of staining reagents (Ehrlich's hsema- 

 toxylin and Czokor's alum cochineal), a diffusion of the chromatin 

 from one of the two nuclei of the maturing pollen grain into the 

 pollen cell, and this diffusion continues till, finally, there is, com- 

 paratively, little chromatin left in the shrunken nucleus.* While^ 

 the diffusion is taking place, the chromatin is more abundant in the 

 immediate neighbourhood of the nucleus. Now in such maturing 

 pollen grains, hardened in alcohol, there is produced by ammonium 

 sulphide after several days' stay in the warm oven, an iron reaction, 

 corresponding in intensity and distribution with the colour produced 

 by the staining reagents, diffuse in the nucleus, strongly marked in 

 its neighbourhood, and slightly at the periphery of the cell. As the 

 maturation of the pollen grain progresses, the iron reaction is more 

 readily obtainable, and, when the maturation is apparently complete, 

 the pollen cell gives, with freshly prepared ammonium sulphide, in a 

 few hours a light green reaction which becomes but a shade deeper 

 after several days' stay in the warm oven. 



Mr. Bensley has also been able to determine with the ferrocyanide 

 mixture the passage of iron salt along the bast portion of the fibro- 

 vascular bundles in the ovary after the opening of the flower, and he 

 has traced these iron salts in sections of the ovary through the raphe 

 of the ovules up to the boundary line of the latter. Beyond this point 

 the iron salts, if they advance, become hidden or disposed of in such 

 a way that they no longer give reactions with acid solutions of potassic 

 ferrocyanide or ferricyanide. Nor do sections of the ovules show any 

 reaction with warm ammonium sulphide, either under a cover-glass 

 or in the bottle. Taught by the experiments on animal cells, I teased 

 out with goose-quill points sections of the ovules in ammonium sul- 

 phide and glycerine on the slide, so far as to isolate the various parts 

 of the ovule, and, after keeping the preparation in the warm oven 

 for three days, the nuclei of nearly all the separate and individual 

 cells showed a dark green reaction, which was due to the presence of 

 iron, as the application of a mixture of dilute hydrochloric acid and 

 potassic ferricyanide proved. I have been able in this way to deter- 



* A similar diffusion of nuclear substance into the pollen cell takes place, 

 according to Strasburger, in those Angiosperms in which each pollen grain develops 

 numerous pollen tubes (' Sitzungsber. der Niederrhein. G-esell. fur Natur- und Heil- 

 kunde,' December, 1882, referred to in Just's ' Botanische Jahresberichte ' for that 

 year). 



