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are to be seen flowing from one part to another in a regular stream, 

 generally to and from the nucleus. This may be seen in many 

 plant hairs, as in those of the stinging nettle, and the stamens of 

 the spider worts ; in other cells the whole protoplasm moves, 

 carrying with it nucleus and granular contents, all of which rotate 

 in the cell, moving up one side and down the other, as may be 

 observed in valisneria. anacharis or nitella, and hydrocharis. In 

 the second ease the mass of protoplasm not only changes its external 

 form, but also its position, with movements similar to those of the 

 amoeba, or of the white corpuseules of the blood. These motions 

 occur in a small pulsating vacuole, and are called amoeboid. They 

 also occur in some fungi and are particularly noticeable in the 

 swarming stages of myxomycetes of plants affected by this fungus. 

 In the diseased cells of the root, may be found a semi-translucent, 

 frothy, and granular, slimy mass of protoplasm, which, under the 

 microscope can be seen to undergo slow movements. The isolated 

 spores after a time swell and burst, and the contents escape and at 

 once begin to move about quite independently as wriggling little 

 bodies called Myxamcebce. These tiny specks of naked protoplasm 

 have powers not only of movement but even of changing their form. 

 They exactly resemble the amoeba in this respect, whilst within 

 them a small round clear space, known as the pulsating vacuole, 

 appears, grows slowly larger and then closes up and disappears, 

 to reappear again in a similar way. 



Movements of the points of the roots. Mr. Darwin has shown 

 that the tips of the radicles of seedlings are sensitive to various 

 stimulauts, especially to very slight pressure, and, when thus 

 excited, they transmit an influence to the upper part, causing it to 

 bend from the pressed side. In some seedling plants the uppermost 

 portion alone is sensitive to light, and transmits an influence to the 

 lower part causing it to bend. If the tip of a radicle is subjected 

 to the vapour of water proceeding from one side, the upper part 

 bends to this side, but it is the tip which is chiefly sensitive to the 

 attraction of gravity, and causes the adjoining parts of the radicle 

 to descend towards the centre of the earth. 



ISumerous experiments upon the tips of the radicles of various 

 plants showed that in most instances they were sensitive to contact 

 of any small object, like a piece of card, or to dry caustic, as well 

 as to slight injury ; this peculiar form of sensitiveness is confined 

 to the tip of the radicle for the length of To millimetres. When this 

 portion is irritated the upper adjoining part of the radicle for a 

 length of 6 to 12 millimetres is excited to bend away from the side 

 which has been acted upon. The curvature thus caused is generally 

 symmetrical, it sometimes occurs six or eight hours after the tip 

 has been irritated, but always within twenty-four hours. Occasion- 

 ally the tip from being constantly acted upon bends upwards, and 



