830 
MR. W. GARDINER ON THE CONTINUITY OF THE 
is insoluble in ammoniacal cupric oxide, and moreover it gives with Chlor. Zinc Iod. not 
the customary blue but an intense red-brown coloration. Lastly, the result with 
Hofmann’s blue appears to point to a protoplasmic character, opposed to which con¬ 
clusion is the fact that it dissolves in sulphuric acid. Thus the question appears to 
be, whether it is related to protoplasm or to cellulose, or whether it consists of 
a modified cellulose basis permeated by a protoplasmic structure.* This, however, 
minute study of development alone can decide, but the point I wish to bring forward 
is the fact that it is coloured by dyes which especially stain the protoplasm. 
There is a curious parallelism in the action of callus towards Hofmann’s blue and 
of pit membrane towards methylene blue, after treatment with the same reagent 
(viz. : sulphuric acid) which may perhaps be worth mention. 
If a section of a second year stem of e.g., Vitis vinifera, be treated with Hofmann’s 
blue it will be found that both the protoplasm and the callus will be stained. If, 
however, sulphuric acid be allowed to act before staining, the callus will naturally 
be dissolved and will no longer colour, and only the protoplasm will be left stained. 
If in the same way a section of pitted tissue, e.g., pulvinus of Robinia, be treated 
with methylene blue, both the cell wall and the pit membrane become coloured. But 
if the section be first treated with sulphuric acid, the swollen or dissolved cell wall 
will remain unstained and only the closing membrane and the sides of the pits will 
alone be stained blue. 
Now, if it be allowed that callus may be regarded as altered protoplasm, it might 
be suggested from the foregoing reactions that cell wall is to be looked upon as 
altered pit membrane, or rather that pit membrane is to be regarded as consisting 
of cell wall that has retained its original properties and has undergone comparatively 
little chemical change. However, I prefer at present to draw no definite conclusions 
from these observed phenomena but merely desire to put forward the facts.! 
On the structure of pulvini. 
Having thus treated of the methods employed, and made some remarks as to the 
nature of the pit membrane, 1 am now in a position to proceed with the description of 
my investigation of the structure of pulvini. This work was commenced in the 
Wurzburg laboratory in the month of July, 1882, under the direction, and at the 
suggestion, of Professor Sachs. 
I studied in detail the pulvini of Mimosa pudica, Robinia pseudacacia, Amicia 
* See Russow’s observations on Abies Picta, ‘ Stzb. d. Dorpat. Naturf. Gesell.,’ 1881, p. 70. Also 
Strasburger, ‘ Bau und Wachsthum,’ p. 60. Russow (‘ Stzb. d. Dorpat. Naturf. Gesell.,’ Feb. 17th, 1882), 
like myself, in contradistinction to Janczewski (‘ Mem. de la Soc. des Sc. Nat. et Math, de Cherbourg.,’ 
vol. xxxiii., p. 209, 1882), believes that the reactions of callus point essentially to its protoplasmic nature. 
f I find in reality that the above reaction of the pit membrane with methylene blue takes place in 
consequence of the fact that the membrane is more resistant than the rest of the cell-wall. Whether 
this is in consequence of the presence of protoplasm in its structure remains to be proved. This 
Strasburger also found to be the case. See ‘ Bau und Wachsthum,’ p. 16. 
