100 Mr W. Gardiner, On the constitution [Feb. 11, 



occurs. The conversion o'f a portion of the cellulose substance into 

 mucilage may take place in such a manner, that the degeneration 

 is almost entirely limited to the middle lamella, or it may extend 

 to several layers of the wall, or finally, mucilage may be detected 

 throughout the entire substance of the cell -membrane. 



The phenomenon of mucilaginous degeneration was strikingly 

 brought to my notice during my research upon the continuity of 

 the protoplasm through the walls of vegetable cells 1 . As I have 

 already stated in my papers upon that subject, I found that 

 Hofmann's aniline blue was an especially good stain for the 

 protoplasm, and I have in consequence used it for staining the fine 

 protoplasmic threads which traverse the cell-wall. In the course 

 of the investigation I repeatedly observed, that in many, cases a 

 very marked colouration took place, not only of the protoplasmic 

 threads, but also of the most external layers of the cell-walls, and 

 in certain instances, e.g. Ghara foetida and the endosperm cells of 

 Tamus communis, the whole of the walls were distinctly blue. The 

 colouration was usually not well defined, but was darkest next the 

 middle lamella and gradually faded off towards the cell-lumen, as 

 for example, in most collenchymatous hypodermal cells, and the 

 cortical cells of the petiole of Ilex aquifolium, Aesculus hippocas- 

 tanum, &c. In some exceptional instances however, e.g. Aucuba 

 Japonica, a very definite staining did occur, of what one might 

 speak of, as a well-defined intercellular substance, which could 

 hardly be distinguished from the almost similarly stained proto- 

 plasm. I had intended to investigate the subject further, and on 

 that account did not treat of it in my paper in Sachs' Arbeiten 2 , 

 since my observations were still incomplete. Quite recently 

 however the matter was again brought very forcibly to my notice, 

 on account of certain passages which appear in a preliminary 

 communication I received from Prof. Kussow 3 on "the connection 

 of the protoplasmic bodies of neighbouring cells," in which he 

 announces the discovery of an intercellular protoplasm, between 

 the cortical parenchyma cells of Acer and Fraxinus and in the 

 same cells of the rhizome of Iris, &c. 



In consequence of this I again renewed my investigations, and 

 as a result, I find, that both Hofmann's blue and water blue (one 

 or the other of which Kussow most probably used 4 ) stains not only 



1 Gardiner, Arbeiten des botanisclien Instituts in Wiirzburg, Bd. in. Heft. i. 



2 Gardiner (loc. cit.). 



3 Kussow, Sitzber. der Dorpat: Naturfors. Gesell. September, 1883. In this paper 

 Kussow confirms in a most striking manner, the results I have already obtained as 

 to the communication of the protoplasmic contents of adjacent cells by means of 

 the sieve-like perforation of the pit-closing-membranes. I have only in rare 

 instances, e.g. parenchyma cells of Aucuba Japonica, seen the nodular swellings of 

 the connecting protoplasmic threads, of which he speaks. 



4 See Gardiner, Phil. Trans, p. 829. 



