30i WALTER GAEDINEE. 



The first experiments were made upon Nierembergia 

 (printed Norembergia) gracilis.' He took pieces of the 

 flower — whether calyx, corolla, stamens, or pistil does not 

 transpire — treated them with a 2 per-cent. solution of silver 

 nitrate for half an hour, or with a "5 per-cent. solution of gold 

 chloride for forty minutes, washed, exposed to daylight, and 

 examined. The silver nitrate preparations when seen from the 

 surface, showed the cell walls stained dark brown, and demon- 

 strated that every here and there were interruptions in their 

 continuity. I have unfortunately been unable to obtain flowers 

 of this plant, and have in consequence not had any opportunity 

 of making this observation for myself, but I should like to 

 point out that such pronounced and frequent interruption is 

 quite opposed to our present knowledge, and certainly to the 

 results I myself have obtained. It is much more probable that 

 the walls were pitted, and that the pit membrane being thin 

 escaped observation. The same may be said of the figure of 

 the hair of Nierembergia, the transverse walls of which are 

 probably pitted in a similar manner to those of the walls of 

 Athsea hairs, a figure of which occurs in Sach's Text-book.^ 

 If Dr. Elsberg's figure is drawn to scale it can scarcely be 

 wondered at, if he has made a mistake, for his magnifying 

 powers have not been suflSciently high. Very frequently the 

 pit membrane is so thin that without very careful preparation, 

 it cannot be recognised under the highest powers, and in many 

 cases the only way to bring out such a membrane is to stain 

 the protoplasm and leave the membrane unstained, or to stain 

 and swell the membrane itself with Schultz solution (Chlor. 

 Zinc lod.). 



But it was from the study of sections of the petiole of Ficus 

 el as tic a, when treated with silver nitrate, that Dr. Elsberg 

 has obtained his most conclusive results. 



He gives a drawing of one of his preparations, and it is its 

 appearance, and the appended description of it, which, perhaps, 

 forms the most startling part of the whole paper; for we are 



^ " Nierembergia gracilis," Hook, ' Bot. Mag.,' 58, 310S. 

 " Loc. cit., p. 43. 



