HARDWICKE'S SCIENCE- GOSSIP. 



219 



widely known, and every housewife should be able 

 to discriminate them, especially as they have all well- 

 marked characters. Amongst these may be men- 

 tioned — Agaricus procerus, Scop. ; A. gambosus, Er. ; 

 A.nebularis, Batsch'; Lactaiius deliciosus, Er.; Copri- 

 nus comatas,~Ei\; Cantharellus cibarius, Er. ; Hydnum 

 repcuulum, L. ; Boletus edulis, Bui. ; Lycoperdon 

 giganteum, Batsch ; and Fistulina hepatica, Er.* 

 Occasionally wc hear vegetarians say they live upon 

 some fabulously small sum, — a few pence per diem ; 

 and although very few people, indeed, would care 

 to debar themselves of wholesome nutritious food 

 for the sake of a mere] theory; yet, it cannot 

 be overlooked, that the continued and continuing 

 increase of the population will eventually demand 

 a full development of the resources of the country. 

 There cannot be a doubt that the esculent species 

 of fungi will, in the future, occupy a most import- 

 ant place in the dietary of the nation, not simply 

 because of their cheapness, but rather by reason of 

 their nutritious qualities and the large proportion of 

 nitrogenous compounds they contain. 



.THE MICROSCOPY OE STARCH. 



rpHERE is, perhaps, no substance in the vege- 

 -*- table economy so important as starch, entering 

 as it does largely into the composition of all classes 

 of the Vegetable Kingdom, with the exception of the 

 Eungi and a few of the Algse and Lichens. And its 

 still greater importance as forming a large propor- 

 tion of the food of man, two-thirds of the human 

 race subsisting on starch, alone renders it worthy of 

 more careful study at the hands of microscopists 

 and histologists than it has hitherto received. 



Before going into its structure, let us look a little 

 at the special function of starch as regards vegetable 

 existence. Starch may be said to be to plants what 

 fat is to animals — a reserve fund for the purposes of 

 nutrition. 



Plants produce by assimilation a larger quantity 

 of formative organizable matter than they can re- 

 quire or employ at the time for cell growth ; this is 

 stored up in cells for future use as protoplasm, and 

 in a much larger quantity as starch. 



Starch always appears in an organized form as 

 solid, rounded, or angular transparent granules, 

 having stratified structure ; their earliest appearance 

 being as small bodies in the protoplasm, from which 



* Any one desirous of learning how to recognize edible 

 and poisonous species should get Mr. W. G. Smith's " Mush- 

 rooms and Toadstools " (R. Harrtwicke), and with" a little 

 care and ordinary attention no difficulty will be experienced in 

 obtaining the necessary information. It is best to bejiiu with 

 some easily-recognized species, as A. procerus, L. deliciosus, 

 or, best of all, the Giant Putf-ball. Should any one be really 

 desirous to be^in fungiis-eating, but lack the necessary 

 courage for the first attempt, from a fear lest he may 

 have mistaken the species, if he were to send a specimen 

 post-paid to the writer, or to almost any fungus-eater, he 

 would most likely get a post-card stating the nature of the 

 specimen by the next post. 



they receive growth and nourishment. And though 

 the actual chemical nature of the formative material 

 is still unknown, it is probable, as pointed out by 

 Sach, that it is formed by chemical or physical 

 changes from the sugar contained in the protoplasm. 

 The next period in the life-history (if such a phrase 

 be applicable) of starch is its assimilation as it 

 develops and increases in size. It is well known 

 that assimilation, being a process of deoxidation, 

 can, with little exception, only take place in those 

 organs that contain chlorophyl, and under the in- 

 fluence of sunlight. 



Thus, starch is a carbon hydrate formed in chloro- 

 phyl by the decomposition of carbon dioxide and 

 water under the influence of sunlight, or, as is now 

 known, by the red, orange, and yellow rays of the 

 solar spectrum with a little of the green, for it has 

 been ascertained that the blue, indigo, and violet 

 rays possess little or no assimilating power. In a 

 paper recently contributed by Mons. Boehm to the 

 Vienna Academy, it is stated that ,s the intensity of 

 light which renders green plants capable of decom- 

 position of carbonic acid, causes also a passage 

 of the starch from the stem into the chlorophyl 

 granules," so, according to this authority, it is 

 " incorrect to say that all the starch that makes its 

 appearance in starchless chlorophyl granules, when 

 exposed to full daylight, is an immediate assimila- 

 tion of carbonic acid." Later on, in the same 

 paper, however, the same writer says, " By cutting 

 starchless primordial leaves of the scarlet-runner in 

 direct sunlight, and in an atmosphere containing 

 8 per cent, of carbonic acid, a demonstrable quantity 

 of starch is formed within ten to fifteen minutes, 

 while in leaves that were agitated in free air this 

 only happened in three-quarters of an hour. " It is 

 not improbable," the same observer sums up, " that 

 the carbon of the decomposed carbonic acid unites 

 immediately with water to form starch." 



After undergoing assimilation in the leaves, 

 starch undergoes a variety of chemical metamor- 

 phoses as it passes through the various tissues of the 

 plant. Thus, in the potato it passes through the 

 tissues of the stem in the soluble form of glucose, 

 being again deposited in the tubers as starch 

 granules. Glucose or grape sugar is in reality 

 simply a combination of starch with the elements 

 of water, as seen from its formula, starch being 

 C V 2 H 20 O 10 , and glucose C12 Ho 4 "Or2. 



Having described the general functions of starch 

 and its mode of formation, we will turn our atten- 

 tion to the granules themselves. These vary in 

 form and size from the -^hy to the ^^0 °f an 

 inch in different plants. In the centre of each 

 granule or at its side or end is a nucleus, or hilum, 

 as it is usually termed, from the old mistaken idea 

 that the granule was by it attached to the cell-wall. 

 Round the nucleus as a common centre are a 

 number of granuiar layers intervened with water 

 and sometimes air, the nucleus being the softest 



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