THE YOUNG NATUBALIST. 



Ill 



apart to perform peculiar functions, till 

 ultimately we have the most complex 

 mechanism manifesting consciousness and 

 intelligence. We cannot stay to define just 

 now the border line, or debateable land 

 betwixt the animal and vegetable kingdoms ; 

 suffice it to say that generally speaking, 

 vegetables obtain and assimilate their food 

 from the inorganic world, and possess the 

 bowers of nutrition and reproduction only ; 

 whilst in the animal world the food must be j 

 in an already organised form, to be fit for j 

 their digestion. In other words vegetables 

 construct or form protoplasm or protoplasmic 

 compounds, out of the mineral kingdom and 

 the waste products of the animal world ; 

 whilst animals devour, assimilate, break-up, 

 and re-arrange already formed protoplasm, j 

 Protoplasm in its pure state is rarely met with 

 in the vegetable world, except in the repro- 

 ductive organs of various seaweeds, &c. But 

 as we have seen, it is always present and 

 associated with life and growth. In the most j 

 lowly organised plants, such as the familiar i 

 yeast plant ( Torula ) we have the simplest form 

 of plant life : a solitary isolated cell so small j 

 as to be individually invisible until magnified 

 by the microscope, yet being potent with life, 

 having the power of growth and multiplying | 

 with almost inconceivable rapidity : yet these | 

 minute plants may be said to consist of 

 Nothing but protoplasm, from or by which is j 

 secreted a surrounding wall of cellulose, a I 

 substance closely resembling starch in its j 

 composition, only it is always found in the 

 form of thin laminae or plates, whilst starch 

 is in the form of grains, a somewhat similar 

 plant forming the green scum on stagnant 

 rain water in Summer, and the red snow of 

 the Arctic regions (Protucoccus) secretes from 

 its protoplasm, minute granules of chlorophyll 

 (from chloros, green, and phyllon, a leaf), which 

 is the source of the green colour in plants, 

 and is found in all the higher plants. It has 

 the peculiar property of absorbing and fixing 

 the carbonic acid gas found in the air, which 

 is the source of the carbon which forms the 



great bulk of the tissues of all plants. These 

 lowly organisms are called unicellular plants, 

 because they are composed of only a single 

 cell, that is a minute sac bladder of cellulose, 

 filled chiefly with protoplasm and water : 

 yet these crude organisms have the power of 

 breaking up the medium in which they float, 

 absorbing and utilising part for their own 

 use, and rejecting the unassimilable portions ; 

 thus changing the appearance and character 

 of the substance in which they are immersed, 

 as may be easily seen by watching the effect 

 of a small piece of yeast put into a quantity 

 of warm sweetened water. As we advance to 

 more highly organised plants, such as the 

 Charas, — an abundant water weed of still 

 lakes and pools, — the water thyme {Anacharis) , 

 or the stinging hairs of th£ common nettle, 

 we find the cells, although forming only part 

 of a plant, individually much larger, and in 

 them, under a moderately magnifying power, 

 most interesting motions of the protoplasm 

 may be observed : sometimes it will contract 

 around the nucleus and gyrate round the 

 walls of the cell ; then it will spread out, and 

 portions will stream away like rivulets to be 

 again withdrawn, never resting but constantly 

 assuming fresh shape and form, and ever 

 greedily seeking for fresh food that it may 

 grow thereby. In this connection it may be 

 mentioned that the hairs on the leaves of the 

 sundew ( Droscni rotundifolia ), a British 

 carnivorous plant, are furnished with a supply 

 of protoplasm, that they may digest and 

 assimilate the unlucky insects that may 

 happen to alight on them. In all the young 

 growing parts of plants protoplasm, as the 

 actively vital formative fluid, is present, for 

 from and by it all the new portions are 

 formed. It is particularly abundant in the 

 seeds, where it is stored away for the future 

 use of the young plant. In this stage it may 

 remain dormant for an indefinite length of 

 time, till again called into activity during the 

 process of germination by suitable conditions, 

 the most important of which are moisture 

 and warmth. 



