310 WALTER GAEDINER. 



established that alcohol did not interfere with the reduction, 

 I cut sections of petiole which had been for twenty-four hours 

 in absolute alcohol. The sections were washed and manipu- 

 lated as before. However, hardly any reduction was found to 

 have taken place on the cell walls, although the cell- 

 contents themselves exhibited well-marked reduction. This, 

 again, suggested that escaped cell-contents were the cause of 

 the granulation. 



To make this quite plain I took sections which were well 

 reduced, and were in every way satisfactory preparations, and 

 with a camel-hair brush freely brushed their surfaces. Nearly 

 all the granules disappeared from the surface of the cell wall. 

 In the cell lumen they were still numerous where the contents 

 had not fallen away, but the cut surfaces of the walls them- 

 selves were quite clean and bright, and so was the entire thick- 

 ness of the cell wall. 



Again, having taken sections of fresh material, I brushed 

 some well before the treatment with silver nitrate. Others I 

 did not brush. The former showed no reduction. The latter 

 exhibited well-marked granulation in the usual manner. 



If the reduction be allowed to take place in diffused daylight 

 the granules are small. If in sunlight they are large. Con- 

 sequently, one may vary at pleasure the size of the granules, 

 and therefore the size of the meshes of the reticulum. 



I think these experiments have sufficiently established that 

 the appearance described by Dr. Elsberg is simply due to the 

 fact that granules of reduced silver are deposited on the cut 

 surfaces of the cell walls, and that no staining occurs in the 

 substance of the wall itself. The whole appearance of proto- 

 plasmic continuity can be brushed away by mere mechanical 

 means, and the size of the granules can be varied at will. The 

 reduction of the silver in the cell wall is caused by some 

 of the cell contents which have escaped from the cell lu- 

 men. 



The gold chloride preparations are not nearly so successful 

 as the silver nitrate, for much less reduction occurs. I was 

 unable to detect any network in the protoplasm, nor could I 



