PROTOPLASMIC MOVEMENTS. 47 



If T. virginica should not be available, T. zebrina, very widely 

 cultivated in greenhouses for hanging baskets, for covering the 

 front of the stage, and as a creeper on the soil under the stage 

 will serve very well, and this will come in very usefully during 

 the winter portion of the year when the former plant cannot be 

 obtained. In summer, on the other hand, T. zebrina rarely 

 flowers, though it can be induced to do so in a warm house. In 

 all essentials the staminal hairs of the two plants are alike. 



Circulation in Gucurbita Hairs. Still another very favourable 

 object is provided by the hairs which grow upon the youngest 

 shoots of the genus Cucurbita (gourd, pumpkin, vegetable marrow, 

 cucumber, etc.). The preparation is made by removing these 

 hairs at their base by a razor, and placing them in a drop of 

 water on a slide. The stronger hairs are inulticellular at the 

 base, and taper off into a row of cells ; others bear multicellular 

 heads. The protoplasmic network in the cells is finely developed ; 

 it contains microsomes, and, though but sparsely, large, green- 

 coloured Chlorophyll-grains. The nucleus is large, suspended 

 by the threads ; it has a brightly shining nucleolus, and is carried 

 about hither and thither in the cell. Similar movements to those 

 of Trad-escantia are shown also by the hairs which stand in two 

 rows on the corolla tube of species of Lamium (dead-nettle). 

 We select just opened flowers, which are very easy to find from 

 early spring to late autumn. 



Rotation in Hydrocharis. A very peculiar object is provided 

 by the root-hairs of Hydrocharis morsus ranee (the Frogbit). We 

 select for observation fresh young roots with stiff hairs. The 

 hairs are visible to the naked eye. Cut off an entire root-tip, and 

 quickly place it on the slide in a suitable quantity of water. The 

 cover-glass is laid on in the usual way, the largest cover-glass 

 at our disposal being chosen. Owing to the not inconsiderable 

 thickness of the object, however, all parts will not be accessible 

 with a high power, as the objective will usually come into contact 

 beforehand with the cover-glass. These hair-cells are very long 

 and tubular, and, like all root -hairs, unicellular. The abundant 

 cytoplasm which they contain is in active movement, but here 

 there are not numerous thin streams, forming a network, but a 

 single strong parietal stream, returning upon itself. This kind of 

 movement is called Rotation, to distinguish it from the other 

 kind, or Circulation, This stream presents the appearance of a 

 broad, slightly spirally wound band, which, if projected upon a 



