CONTINUITY OF PEOTOPLASM IN CELLS. 215 



the next, bj' means of delicate threads wliich pass through 

 pores in the intervening cell-wall. Doubtful instances afforded 

 by the cribrose-cells have been alreadj- alluded to (see 279). 

 The endosperm cells of seeds of Str3-chnos Nux-vomiua afford 

 a well-marked example of the cases of communication between 

 cells of seeds. TangP advises that very thin sections jjarallel 

 to the flat surface of the seed be shaken with dilute tincture 

 of iodine or with a solution of iodine in iodide of potassium for 

 about five minutes, and then thoroughly washed with pure water. 

 The protoplasmic and other contents of the uninjured cells will 

 then appear as a contracted ball having somewhat the shape of 

 the cell. From the mass in one cell minute threads run through 

 pores or canals in the wall to the masses in the adjoining cells, 

 and there is no break in their continuit}'. In the endosperm of 

 the allied species, Strychnos potatorum, Tangl did not detect 

 canals of the character found in S. Nux-vomica. 



Gardiner'-* has demonstrated the existence of communication 

 between the protoplasmic masses in contiguous cells of the pul- 

 vini of the leaves of some plants having the power of motion. 

 When sections of these lea^■es are placed in a solution of a salt 

 which causes contraction of tiie protoplasm, the shrunken mass 

 is seen to be connected with the cell-wall by extremely delicate 

 threads of protoplasm. The threads can be traced to pits in the 

 wall, and there it can be seen that the}- are exactly opposite the 

 threads on the other side of the wall. If the solution of the salt 

 used is too strong, some of the threads may be ruptured, and 

 then one free end of each thread will retract to the main mass 

 while its other part goes to the cell- wall. If fresh sections are 

 treated with strong picric acid, and then, after washing in alco- 

 hol, are stained with anilin blue, the continuity of the proto- 

 plasm in uninjured cells becomes apparent. Mimosa affords 

 excellent material for this purpose. 



Hillhouse' reports similar continuitj- of protoplasm in the cortex 

 of the stem of Laburnum, and in the petiole of several leaves. 

 The fresh material is to be placed for a few days in absolute 

 alcohol, and the thin sections made from it are to be treated 

 with dilute alcohol. The sections are then to be placed in 

 concentrated sulphuric acid, and after the acid has removed the 

 cell-wall, its excess is to be withdrawn by means of a pipette, 



^ Pi'ingsheim's Jahrbiiolier, 1880, p. 170. 



' Philosophical Transactions Royal Society, 1883, clxxiv. 817. 



s Botanisches Ceiitralblatt, 1-883, -xiv. 8&, -121. - - -, 



