182 Protoplasm through Walls of Vegetable Cells. [Dec. 20, 



IV. " On the Continuity of the Protoplasm through the Walls of 

 Vegetable Cells." By Walter Gardiner, B.A., Scholar 

 of Clare College, Cambridge. Communicated by W. T. 

 Thtselton-Dyer, C.M.G., F.R.S. Received December 13, 

 1883. 



Since the communications of November 11th, 1882, and April 16th, 

 1883, the author has been chiefly employed in testing and improving 

 his methods, and adding to the number of plants in which he has 

 been able to demonstrate the existence of a continuity of the proto- 

 plasm between adjacent cells. In certain endosperm cells, e.g., 

 Bentinckia Conda-panna, where the protoplasmic threads traversing 

 the cell walls are particularly well developed, it is possible to see the 

 threads perfectly clearly by merely cutting sections of the endosperm, 

 and mounting them in dilute glycerine. Taking the structure dis- 

 played by such a preparation as normal, the author has compared it 

 with the preparations obtained after the action of Chlor. Zinc. Iod. 

 and sulphuric acid. He finds that his method of swelling with Chlor. 

 Zinc. Iod., and staining with Picric- Hoffmann Blue, is in every way 

 perfectly satisfactory, since but little alteration of the structure 

 occurs, and the staining with the Picric-Hoffmann Blue is limited to 

 protoplasm. The sulphuric acid method is in the main unsatis- 

 factory, although it is valuable in the case of thin-walled tissue, 

 where violent swelling must be resorted to ; and it is also valuable as 

 affording most conclusive evidence of the existence of a protoplasmic 

 continuity in those cases where the protoplasmic processes of pits cling 

 to the pit-closing membrane. He believes, however, that the results 

 obtained can only be rightly interpreted in the light of the results 

 obtained with Chlor. Zinc. Iod. The possibility of seeing the threads 

 depends upon their degree of tenuity and upon the thickness of the pit- 

 closing membrane, and in extreme cases and in what are by far the more 

 general cases, the only evidence of such perforating threads is afforded 

 by the general staining of the pit-closing membrane. Every tran- 

 sition between clearly defined threads in the substance of the closing 

 membrane and the mere staining of that structure as a whole occurs. 



The author has found that in all pitted tissue a pit-closing mem- 

 brane, which is made evident by staining thin sections with iodine 

 and mounting in Chlor. Zinc. Tod., is uniformly present, and that open 

 pits do not occur. The continuity of the protoplasm is always esta- 

 blished by means of fine threads arranged in a sieve-structure, and 

 not by means of comparatively large processes which the occurrence 

 of open pits would necessitate. He cannot therefore agree with ob- 

 servers whose statements necessitate the existence of such open pits. 



Since the last communication the author has been able to observe 



