309 



PINQUICULA VULGARIS. 



[Chap. XVL 



fly, showed a trace of incurvation after 3 hrs., and this became 

 strongly pronounced in 7 hrs. After 24 hrs. the infolded edge waa 

 only .10 of an inch (4.0G4 nun.) from the midrib. The margin now 

 began to unfold, though the lly was left on the leaf; so. that by the 

 next morning (/. e. 48 hrs. from the time when the fly was first 

 put on) the infolded edge had almost recovered its original posi- 

 tion, being now .3 of an inch (7.02 mm.), instead of .16 of an inch, 

 from the midrib. A trace of ile.xure was, however, still visible. 



Uxiicrimcnt 6. A young and concave leaf was selected with its 

 margins slightly and naturally incurved. Two rather large, ob- 

 long, rectangular pieces of roast meat were placed with their ends 

 touching the infolded edge, and .40 of an inch (11.68 mm.) apart 

 from one another. After 24 hrs. the margin was greatly and 

 equally incurved (see Fig. 16) throughout 

 this space, and for a length of .12 or .13 of an 

 inch (3.048 or 3.302 mm.) above and below 

 each bit; so that the margin had been af- 

 fected over a greater length between the two 

 bits, owing to their conjoint action, than be- 

 yond them. The bits of meat were too large 

 to be clasped by the margin, but they were 

 tilted up, one of them so as to stand almost 

 vertically. After 48 hrs. the margin was al- 

 most unfolded, and the bits had sunk down. 

 When again examined after two days, the 

 margin was quite unfolded, with the excep- 

 tion of the naturally inflected edge; and one 

 of the bits of meat, the end of which had at 

 first touched the edge, was now .067 of an 

 inch (1.70 mm.) distant from it; so that this 

 bit had been pushed thus far across the blade 

 of the leaf. 



Experiment 7. A bit of meat was placed 

 close to the incurved edge of a rather young 

 leaf, and after it had re-expanded, the bit 

 was left lying .11 of an inch (2.795 mm.) 

 from the edge. The distance from the edge 

 to the midrib of the fully expanded leaf was 

 .3.5 of an inch (8.89 mm.); so that the bit 

 had been pushed inwards and across nearly one-third of its semi- 

 diameter. 



Experiment 8. Cubes of sponge, soaked in a strong infusion of 

 raw meat, were placed in close contact with the incurved edges of 

 two leaves, an older and younger one. The distance from the 

 o<lge8 to the midribs was carefully measured. After 1 hr. 17 m. 

 there appeared to ho a trace of incurvation. After 2 hrs. 17 m. 

 both leaves were plainly inflected ; the distance between the edges 

 and midribs iM'ing now only half what it was at first. The in- 

 curvation increased slightly during the next 4J hrs., but remained 

 nearly the same for the next 17 hrs. 30 m. In ^~y hrs. from the 

 time when the sponges were placed on the leaves, the margins 



Fio. 16. 



(PinguictUa vulgaris.) 

 Outline of leaf, with 

 right murKin in- 

 flected against two 

 square bite of meat. 



