52 I). P. Penhallow — Tendril Movements in 



For permanent preservation, the sections may be mounted 

 directly in glycerine jelly, or they may be washed out in 

 water, cleared up for a few seconds in concentrated carbolic 

 acid* and then mounted in chloroform balsam. Either method 

 gives very satisfactory preparations, though the former is pre- 

 ferable. 



The results obtained by this process are most satisfactory, 

 particularly in the collenchyma tissue (fig. 6). There the walls 

 become strongly swollen, and the protoplasmic connections are 

 sharply defined as blue threads running through the colorless 

 walls (fig. 7). Salt solution does not give so satisfactory re- 

 sults, through its failure to properly swell the cell wall, which 

 is essential, while on the other hand, the cellulose reaction 

 developed in the collenchyma .under the action of chlor-iodide 

 of zinc, renders this process of little value in this particular 

 case, as there is then too little distinction between the blue fila- 

 ments and the blue cellulose of the cell wall. 



It is thus clearly demonstrated that there is a distinct con- 

 tinuity of protoplasm through the living tissues of the tendril, 

 particularly in the collenchyma (fig. 7), and this must have 

 an important bearing upon the transmission of impulses, e. g., 

 those produced by irritation, from one portion to another. 



Externally, the form of the tendril arm is that of a long fila- 

 ment, well-rounded on the lower side, but flattened and even 

 slightly channeled above. The extremity, for a distance of half 

 or three-quarters of an inch, takes a more perfectly rounded 

 form and turns slightly downward, the concave side of the 

 curve being that which is always the more sensitive. The lower 

 surface, which is almost entirely free from epidermal hairs, is 

 always the most sensitive to contact, curvature being readily 

 produced by contact of the finger with it, though the same 

 effect is not produced upon irritating the upper side. A curve 

 in one direction as the result of irritation, is removed only 

 after the lapse of some little time, when, by continued growth, 

 the opposite sides become equal in length. The lower side is 

 the one which, in the majority of cases, first comes in contact 

 with an object of support, and in any case, it is finally the side 

 toward which the bending most strongly tends. 



In one case, a tendril irritated on the lower side by the finger, 

 coiled upon itself completely in one minute. The cause of irri- 

 tation removed, the tendril straightens out again, provided it is 

 not already too far advanced in age, or the irritation is not too 

 long continued. Slight pressure such as would be caused by 

 small loops of thread, also often exert a definite influence. 



* Phenol used in this way gives most satisfactory results as a clearing reagent, 

 and for a long time has with us, replaced turpentine entirely. Jour. Royal Mic. 

 Soc, vol. hi, pp. 693 and 858. 



