1887.] Contractility of the Protoplasm of Plant Cells. 17 



— and of Monge long previously. In this paper it is applied, first to 

 the non-analytical exposition of the differential criteria of algebraic 

 functionality given by Jacobi, and then to the discussion in a similar 

 manner of the theory of partial differential equations of the first and 

 second order, particularly those named after Lagrange, Monge, and 

 Ampere. 



VI. " On the Power of Contractility exhibited by the Proto- 

 plasm of certain Plant Cells." (Preliminary Communi- 

 cation.) By Walter Gardiner, M.A., Fellow of Clare 

 College, Cambridge, Demonstrator of Botany in the Uni- 

 versity. Communicated by Prof. M. Foster, Sec. R.S. 

 Received November 21, 1887. 



In a former communication (' Roy. Soc. Proc.,' ~No. 240, 1886), 

 some account was given of the principal changes which take place 

 in the gland cells and stalk cells of Drosera dichotoma during secre- 

 tion. The present paper deals with certain experiments and observa- 

 tions which were undertaken in order to attempt to ascertain by 

 what mechanism the bending of the tentacles is made possible in 

 Drosera, and what changes occur in the tentacle cells. 



During actual movement no obvious histological changes can be 

 detected in the cells of the bending portion, but when the tentacle 

 has become well inflected, it becomes apparent that the cells of the 

 convex side become more, and those of the concave less . turgid than 

 before. Some time after stimulation, and when the period of aggre- 

 gation has set in, it can be observed that the cells of the convex side 

 are less aggregated than those of the concave. Having ascertained 

 that of the dye solutions, eosin, and of salts, the salts of ammonia, 

 are readily sucked up into the tissue, it was further noticed that in 

 stimulated tentacles the cells of the convex side readily allow the 

 solutions to penetrate, while those of the concave are only penetrated 

 with great difficulty. Thus in the case of a stimulated tentacle 

 treated with eosin, the convex cells are stained long before the con- 

 cave, and with amnionic carbonate the tannin of the convex cells may 

 be precipitated while the concave cells remain normal, or the convex 

 cells may even be killed while the concave cells remain alive. Thus 

 after stimulation certain changes have occurred in the concave cells 

 of the bending portion, and one result of this change is an increased 

 impenetrability of the primordial utricle. In my former paper I 

 have shown that the tentacle cells of Drosera are very sensitive to 

 contact, for if the gland cells be slightly crushed, all movement of the 

 stalk cells ceases for a time, and the spindle-shaped rhabdoid contracts 

 and tends to become spherical. Bearing in mind also the very pro- 



