348 



SPONTANEOUS MOVEMENTS IN TLANTS. 



diurnal to the nocturnal position, and the contrary ; but the lateral 

 ones are continually rising and falling, both day and night, by a suc- 

 cession of little jerks, like the second-hand of a time-keeper , the 

 one rising while the other falls. Exposure to cold, or cold water 

 poured upon the plant, stops the motion, which is immediately re- 

 newed by warmth. The late Dr. Baldwin is said by Nut-all to 

 have witnessed the same thing in our own Desmodium cuspidatum, 

 in Georgia ; but the observation has never been confirmed. In 

 several tropical Orchideous plants, and especially in a species of 

 Megaclinium, the lower petal, or labellum, executes similar spontane- 

 ous movements, with great freedom and pertinacity. Such phenom- 

 ena, occurring as they do in Pha?nogamous plants of ordinary struc- 

 ture may serve to render more credible the true vegetable character 

 of the 



G78. Free Movements of llic 



Spores of AlgCC, and the cor- 

 puscles or spiral filaments of 

 the antheridia of most Cryp- 

 togamous plants, already re- 

 ferred to (G59 - 6G3). The 

 spores of most of the lower 

 Algaa are now known to ex- 

 hibit this peculiar activity 

 at the time of their discharge 

 from the parent cell, when, 

 for rorae moments, or usual- 

 ly for several hours, they 

 behave like infusory ani- 

 mals, executing spontaneous 

 mo'.'ements in the water, 

 until they are about to ger- 

 minate. This singular move- 

 ment was first detected many 

 years ago in Vaucheria G39 MJ 6;i e " w 



FIG. C36. 1'ruiting end of a plant of Vaucheria geminata (after Thuret); one cf the 

 branches still containing its spore 637 Moving spoie just escaped from the apex of the 

 other branch ; the ciliary apparatus seen over the whole surface C38. Spore in germination. 



FIG 639-642. Successive steps in the germination of (Edogouium (Conferva) vesicata. 

 643 The plant developed into a series of cells, four of which display the successive steps in tho 

 formation of a spore. 644 The locomotive spore with its vibratile cilia (copied from Thuret). 

 When tho movement ceases, and it begins to gcrmiuate, it appears as in 639 (The antheridia 

 or fertilizing apparatus of these plants were not Unowu when these figures were made.) 



