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HARD WICKE'S SCIENCE-GOSSIP. 



peculiar, sometimes (as in Agaricus mellens) it causes 

 a cold sensation at the back of the ears, and swelling 

 of the throat ; at others (as in Marasmhis caulicinalis), 

 the taste proves to be intensely bitter ; some are so 

 fiery (as in Lactarius turpis, bleimius, and acris), that 

 the smallest piece placed upon the tongue resembles 

 the contact of a red-hot poker." Their odour he 

 also found to differ: " many are very pleasant, like 

 meal ; a few are sweet ; some resemble stinking fish 

 (as Agaricus cucumis) ; one, mice (as A. incanus) ; 

 another, camphor ; whilst Marasmhis fcetidus, and 

 impudicus are like putrid carrion ; others are like 

 burnt flannel, garlic, rotten beans, and almost every 

 imaginable disagreeable thing (W. G. Smith in 

 "Science Gossip"). 



Unfortunately there is no "golden rule" for the 

 discrimination of the edible and noxious species, and 

 a long study, often of purely microscopical details, is 

 required before this can be done with safety. The 

 odour, taste, and general appearance are, however, 

 the most reliable guides Nature has given us in these 

 and other toxic plants. And, roughly speaking, we 

 might say that edible mushrooms generally have a 

 white, creamy or buff colour ; the gills are white or 

 pink, and the stem white or grey ; their taste is mild 

 or sweet, and their odour agreeable ; their white 

 juice does not readily change colour when exposed 

 to the' air, and their flesh is firm. On the other 

 hand, most fungi that are red, scarlet, green or black 

 on the top, those having yellow, red or brownish 

 gills, and a stem of similar colour or perhaps spotted ; 

 all those that have an acrid or burning taste, and an 

 unpleasant smell ; and those that turn blue or red 

 when broken ; that freely secrete a milky fluid, feel 

 slimy and generally flabby — should be avoided as pro- 

 bably dangerous. Amongst the most common of our 

 poisonous species we find : Agaricus vermis, Phal- 

 loides, muscarius, sinuatus, crustuliniformis, pipe- 

 rat us ; Lactarius pyrogalus, acris, rujus ; Russula 

 emetica, Marasmia urcns, and Phallus impudicus.* 



We have now thrown a rapid glance through one 

 of the most interesting pages in the wondrous book 

 of nature. In spite of our, necessarily, somewhat 

 hasty review, we have found, even in the limited area 

 of our British Flora, a formidable array of plants 

 noxious to animal life in a high degree. These un- 

 expected results naturally lead us to enquire : What 

 is the cause of poisons in plants, and how were they 

 produced ? Only one logical answer can be given : 

 They were evolved through the struggle for existence, 

 which, selecting those variations most useful to the 

 plant, gave the most poisonous individuals a better 

 ■chance to live ! 



Poisonous plants do not form a single and isolated 

 group ; they are, as we have seen, scattered here and 



* For further information see " Mushrooms and Toadstools," 

 by Worthington G. Smith (Allen & Co.), with two sheets con- 

 taining altogether sixty excellent coloured figures of edible and 

 poisonous fuDgi. 



there amongst the different orders, nearly every order 

 containing, in some part or other of the world, some 

 poisonous species. We have, likewise, seen that all 

 these plants do not produce the same poisons, 

 although generally all species of an order, or at least 

 of a genus, possess similar properties. We cannot 

 have helped observing that we seldom find two or 

 more poisons, in different plants, of the same nature 

 or intensity, whilst, on the other hand, we can easily 

 trace a perfect series where the toxic properties range 

 from a slight acidity of the sap (as in Rumex oxalis, 

 etc.) to a copious and highly virulent special secretion. 

 These secretions, again, may be found either all 

 over the plant, or they may be produced in particular, 

 often very limited organs, as in many seeds (notably 

 the "ordeal beans" of Physostigma), in barks, roots, 

 the "stings" of Urtica, etc. From this follows that* 

 whilst in some plants every part is toxic, in others 

 some parts are not only harmless but indeed highly 

 nutritious (e.g. the potato). And, finally, let me 

 remark that few plants are equally noxious at all 

 periods of their life, as many only reach their highest 

 point of virulence at the time of flowering. I have 

 laid so much stress on this tendency to vary because it 

 is this that has enabled natural selection to preserve 

 the most poisonous plants of any given group, and 

 thus to give rise to more highly toxic varieties and 

 species. 



Plants form the natural food of animals, and are 

 continually destroyed in incredible numbers by multi- 

 tudes of snails, insects, birds and mammals. It is 

 evident that any species possessing no defences (or 

 one the defences of which had ceased to be adequate 

 to new requirements) would soon be exterminated — 

 as many doubtless have been. Mechanical defences 

 such as thorns, spines and hairs, though forming a 

 good protection against some of their foes, are soon 

 overcome by others, and it is plain that no plant 

 could be better protected, than by having properties 

 noxious, or at least distasteful, to most animals prey- 

 ing on it. Now, any animal coming to feed on a 

 bed of growing plants, such as we often see in the 

 spring, would naturally select for food those most 

 agreeable to the taste, or, if all happened to be seed- 

 lings of a poisonous species, it would eat the least 

 loathsome. In this way, the animal would uncon- 

 sciously favour the most virulent plants, not alone by 

 letting them grow on, but also by clearing the ground 

 of species or individuals that would have competed for 

 moisture, soil, air, and light. They would then grow 

 strong, perfect, and produee healthy seed inheriting 

 their toxic, but for the plants useful properties. We 

 have only to allow sufficient time for this unconscious 

 (i.e. natural) selection, of the most virulent from the 

 most poisonous, in different places and by various 

 animals, and in the course of time, may be of ages, 

 we should find numerous plants, all producing 

 poisons, but differing in nature and intensity in all 

 degrees. And this is actually the case ! 



