CIRCULATION IN PLANTS. 



377 



magnifying power from one hundred to two hundred diameters, 

 an appearance such as that shown in fig. 249 will present 



Fig. 248. 



Fig. 249. 



itself; a few flattened cells of the cuticle, def, will then be 

 seen with a spiral vessel, a b, beneath them. In each cell 

 may be observed a motion of oblong green globules creeping 

 round and round in the direction of the arrows ; in some cells 

 a large transparent globule or nucleus is seen, as at f; this 

 also will sometimes be found circulating with the smaller 

 globules. The circulation may also be noticed in sections of the 

 stems of the same plant ; after the section has been made, the 

 circulation is deadened or stopped for a time, but on being 

 allowed to remain quiet for a short time in the water, it will 

 recover its former velocity. 



Tradescantia virginica — Spiderwort. — The circulation in the 

 jointed hair of the filament of the anther of this plant was 

 first discovered by Dr. Robert Brown, in 1828, and has since 

 that time been seen and described by other botanists, and 

 amongst them Mr. Slack, from whose paper the magnified 

 drawing of the hair represented by fig. 250 has been taken. 

 It is composed of three delicate elongated cells, as shown at 

 bed, which rest upon a broader and shorter cell, a, having, in 

 the present case, a few flattened cells of the cuticle of the 

 calyx attached to it. In all the elongated cells, ab c, except 

 d, the circulation can be easily seen with a power from two 



