Oxalis bupleurifolia.—­This species is rendered remarkable by the petioles being foliaceous, like the phyllodes of many Acacias.  The leaflets are small, of a paler green and more tender consistence than the foliaceous petioles.  The leaflet which was observed was .55 inch in length, and was borne by a petiole 2 inches long and .3 inch broad.  It may be suspected that the leaflets are on the road to abortion or obliteration, as has actually occurred with those of another Brazilian species, O. rusciformis.  Nevertheless, in the present species the nyctitropic movements are perfectly performed.  The foliaceous petiole was first observed during 48 h., and found to be in continued circumnutation, as shown in the accompanying figure (Fig. 130).  It rose during the day and early part of the night, and fell during the remainder of the night and early morning; but the movement was not sufficient to be called sleep.  The ascending and descending lines did not coincide, so that an ellipse was formed each day.  There was but little zigzagging; if the filament had been fixed longitudinally, we should probably have seen that there was more lateral movement than appears in the diagram.

Fig. 130.  Oxalis bupleurifolia:  circumnutation of foliaceous petiole, filament fixed obliquely across end of petiole; movements traced on vertical glass from 9 A.M.  June 26th to 8.50 A.M. 28th.  Apex of leaflet 4 ½ inches from the glass, so movement not much magnified.  Plant 9 inches high, illuminated from above.  Temp. 23 1/2o — 24 1/2o C.

A terminal leaflet on another leaf was next observed (the petiole being secured), and its movements are shown in Fig. 131.  During the day the leaflets are extended horizontally, and at night depend vertically; and as the petiole rises during the day the leaflets have to bend down in the evening [page 329] more than 90o, so as to assume at night their vertical position.  On the first day the leaflet simply moved up and down; on the

Fig. 131.  Oxalis bupleurifolia:  circumnutation and nyctitropic movement of terminal leaflet, with filament affixed along the midrib; traced on a vertical glass from 9 A.M. on June 26th to 8.45 A.M. 28th.  Conditions the same as in the last case.

second day it plainly circumnutated between 8 A.M. and 4.30 P.M., after which hour the great evening fall commenced. [page 330]

Averrhoa bilimbi (Oxalidae).—­It has long been known,* firstly, that the leaflets in this genus sleep; secondly, that they move spontaneously during the day; and thirdly, that they are sensitive to a touch; but in none of these respects do they differ essentially from the species of Oxalis.  They differ, however, as Mr. R. I. Lynch** has lately shown, in their spontaneous movements being strongly marked.  In the case of A. bilimbi, it is a wonderful spectacle to behold on a warm sunny day the leaflets one after the other sinking rapidly downwards, and again ascending slowly.  Their movements rival those of Desmodium gyrans.  At night the leaflets hang vertically down; and now