MOl'EMEXTS IX THE OR(EL\S OF PLAXTS ^ 
circle, at other times in an ellipse. Dutrochet, a keen French 
observer, noted the motion of a youn^f growing Pea in a pot, 
placed in a room lighted on one side only. The leaves, he 
observed, soon inclined themselves towards the sky, directing 
their petioles now to the light and again to the darker part of the 
chamber. The tendrils, which are merely the prolongation of the 
midrib of the leaves, were first nearly straight, now curved and 
arched, then waving from side to side, and presenting many 
irregular motions. Me used fixed indicators as slender rods, 
firmly planted in the soil, and was thus enabled to note exactly 
the form and duration of the movements. He found that the 
rachis of the Pea’s compound leaf participated in the movement 
of revolution, or was even the chief agent in it. The tendril, 
during the period of revolution, constantly directed itself towards 
the floor of the room, as though shunning the light, while when a 
revolution would bring it near the light it seemed to hesitate and 
then to retire in the opposite direction. Dutrochet asks. What can 
be the cause of this revolving movement ? It is not re\ ealed to 
the eye, and must therefore be some vital and internal exciting 
cause, to which light contributes nothing, but, on the contrary, 
acts against it, and when very vivid seems to stop it. 
Before concluding this part of the subject, the wonderful 
phenomena connected with the germination of Fern spores, as 
described by Herr Suminski and M. Thuret, will be related. 
To follow the germination of a spore under the microscope, we 
find first that the elastic and coloured shell of the spore is 
ruptured, and through the opening thus formed is protruded a 
sort of tube, which soon lengthens itself by the addition of 
further cells at its extremity. From this at last results a small 
foliaceous, somewhat heart-shaped or pyriform, leaf-like body. 
Its dimensions in Ptcris seymlata are ^ inch by inch. This is 
called the prothallium, and in the upper lobe of this will appear in 
due time a minute rootlet, then the antherid, and lastly the arche- 
gonium. The antherids are small, cellular, teat-like bodies, 
formed of three cellules superimposed on each other; these are 
the antherid cells. The central one is embraced by a second ring- 
like cellule, which is filled with a greyish, granular matter ; by 
degrees small spherical bodies are seen, which are the anthero- 
zoids. As these develop themselves the central ca\ ity increases 
in volume and presses strongly upon the walls of the peripheric 
cellule. Presently the force is so great that the antherid is 
suddenly burst and the antherozoids are expelled at the same 
time. When first set free they appear as little grey spherical 
cells, whose contents are very indistinct. These are immobile, 
but after some minutes they begin to unroll themselves sud- 
denly and dart about in the ambient liquid with inconceivable 
rapidity. They turn themselves about with a gyratory motion, 
which is sometimes continued without interruption for over two 
hours. 
According to M. de Bary, in the third mode of the germina- 
