Francis E. Lloyd — 190 — Carnivorous Plants 



itial closure, there is actual and measurable shrinkage of that sur- 

 face, except where the body of the insect propped it out. AsnroA 

 (1934), we remember, compares this movement with the slow movement 

 which supervenes on "closure" in Aldrovanda, caUing it the "narrow- 

 ing" movement. 



But the main contention of Batalin, in which he was in agree- 

 ment with Darwin, was that during closure there is an actual shrink- 

 age of the upper or inner surface, accompanied by expansion of the 

 lower. This amounts to saying that the tissues including the epidermis, 

 contract in the upper region, and expand in the lower. This was 

 made an issue by Brown (1916). Using again the same method, 

 he found extension in the lower surface and decreases in the upper. 

 But the latter amounts were very small, amounting to only 1.5% 

 of the original distances, while for the lower surface the differences 

 of dimension range between :^.s to 10, or an average of 6.7%. Fur- 

 thermore, and this is of prime importance, Brown found that there 

 is an error of observation due to changed surface curvatures, so that 

 the actual surface retains dimensions which it only seems to lose, 

 since what one measures is not the curved surface, but the chord 

 of its arc. Brown's opinion, based on the measurement of a model, 

 was that "if there is any change in the area of the upper surface 

 during closure it is probably in the direction of an increase rather 

 than in that of a decrease," in this squarely contravening previous 

 opinions. During subsequent opening, however, the reverse obtains. 

 The upper surface now expands (to the amount of 9.4% of the orig- 

 inal measurements) while the under surface maintains its enlargement 

 merely. True there is a small apparent expansion which is attrib- 

 uted by Brown to the same sort of error as that detected in the 

 measurements of shrinkage of the inner surface. It was shown also 

 that as the result of stimulation the growth of the lobes of the trap 

 was greater by a good deal than their growth during a long period 

 when there was no stimulation, from which it appears that stimu- 

 lation is a Hberator of growth and that, accordingly, the responses 

 to stimulation become less vigorous if the stimulus is repeated of- 

 ten. This recalls Batalin's experiments which showed that when 

 a trap was stimulated seven times on ten successive days, the abil- 

 ity to respond was not lost, but was progressively very materially 

 weakened. 



What then takes place during the response movement? Macfar- 

 LANE allowed that the contraction observed by Darwin would be 

 due to the escape of water through pores in the protoplasm, and 

 sought for some visible evidence of such. He ventured to suggest 

 that appearances in the parenchyma cells of the motile tissue, con- 

 sisting of "rows of extremely minute globules or pores in the proto- 

 plasm," suggested a parallel with animal voluntary muscle, and that 

 on ultimate analysis the activity might be explained, as in the case of 

 plant cells, by water movements. This is not the same as saying 

 that "Macfarlane beheved that there are structures in the leaves . . . 

 which resemble animal muscles." 



Batalin, not being able to detect any change in translucence of 

 the tissues, which would be expected if there were any effusion of 



