164 Mr. W. Gardiner. On the Continuity of the [Apr. 26, 



Salix, &c, the closing membranes of the pits were perforated by fine 

 protoplasmic threads. In the present paper the author details his 

 results upon pulvini, treats of the methods employed, and gives an 

 account of his investigations as to the structure of endosperm cells, 

 which were undertaken with the object of controlling his previous 

 researches. Since experiments showed that all preservative reagents 

 were unsatisfactory, fresh material alone was employed. In investi- 

 gating the subject of protoplasmic continuity the method of swelling 

 the cell- wall and subsequent staining was adopted. Either sulphuric 

 acid or chlor. zinc. iod. was used as the swelling agent; and, after 

 washing, the sections were stained with Hoffmann's violet — in which 

 case they were subsequently washed out with glycerine — or with 

 Hoffmann's blue. The latter dye was found to be a particularly 

 satisfactory reagent for staining the protoplasm alone, while methylene 

 blue, on the other hand, especially stains the cell-wall. After the 

 action of chlor. zinc. iod. and subsequent staining it was still found 

 to be impossible to colour the protoplasmic threads running through the 

 cell- wall, and since the author's experiments had led him to believe 

 that this was merely due to phenomena of diffusion (the solution of 

 the colloidal dyes diffusing but little into the colloidal protoplasm), 

 he adopted the modification of dissolving the solid Hoffmann's blue 

 in a 50 per cent, solution of alcohol saturated with picric acid, which 

 was found to be perfectly successful as a stain. 



Having shown that in its reactions the pit membrane differs markedly 

 from the rest of the cell- wall, the author proceeds to give a detailed 

 account of his results with pulvini. In Mimosa, Hobinia, and 

 Amicia, the parenchymatous cells of the pulvini were found to com- 

 municate with one another by means of delicate protoplasmic threads 

 which perforated the closing membranes of the pits. In many 

 instances it appeared as if the thread went bodily through the pits, 

 but the author was disposed to believe that in reality a sieve-plate 

 arrangement was present in every case. The protoplasm of the bast 

 fibres also appear to communicate through the pit membrane by 

 means of a sieve-plate-like structure. Thus from the epidermal 

 cells right up to the last living bast fibre, which impinges on the first 

 dead vessel, a direct continuity from cell to cell has been established, 

 and such a pulvinus may be regarded as a connected whole. The 

 author has observed that a means of communication between adjacent 

 cells appears to exist in the pulvini of Phaseolus multiflorus, and 

 Desmodium gyrans ; in the cells of the leaf of Dionasa muscipula ; in 

 the stamens of Cynara Scolymus, and in tendrils ; but in consequence 

 of somewhat hurried observation, owing to the lateness of the season, 

 he cannot regard these results as entirely conclusive, and intends to 

 work over the subject in further detail on a future occasion. 



In order to clear up certain doubtful points with regard to his work 



