482 



THE GARDENE&& CHfiONlCLR 



[OCTOBEE 2?. 



have made it possible to arrange certain organic 

 compounds on the types of some of the simple inor- 

 ganic bodies. 



One very important suggestion he made was that 

 the weights then usually assigned to oxygen, sulphur, 

 and carbon, ought to be taken just double. This helped 

 to clear up many apparent anomalies. For example, 

 where it was formerly supposed that in a compound 

 there were two atoms of oxygen each with the weight 

 (relative to hydrogen) of 8, he suggested one of Hi ; 

 carbon would be 12 instead of 6, and sulphur 32 

 instead of 16. 



In this rapid historic retrospect much important 

 work has been purposely passed over. The paper 

 would otherwise be too long. 



My aim has been only to draw the attention of culti- 

 vators to the kind of way in which, during the fifty 

 years following the circulation of Dalton's lirst table, 

 our chemistry has come to be what it is ; that is, so 

 far as measuring by volume and weight are concerned ; 

 for this, with temperature observations, is at the 

 bottom of chemistry. 



But this is not all ; especially it is not all in 

 reference to plant life. 



There are compounds which, so far as the relative 

 proportions of the weights of their constituent 

 elements go, appear identical. Their " chemical 

 composition " is the same, yet in certain physical 

 ways they behave differently ; it cannot, therefore, 

 be assumed they are absolutely identical. 



Leaving for the present the different names that 

 have been proposed for these phenomena, let us 

 consider one that has a bearing on starch and 

 sugar. 



It has been just mentioned that there are certain 

 recognised types among compounds. It is not only 

 a matter of convenience, but it seems to accord 

 with the facts of Nature, that these can be thrown 

 into groups, classes, series, or " families." (The use 

 of these terms by chemists is unfortunately by no 

 means uniform any more than is the use of alliance, 

 group, sub-order, &c, among botanists.) One class or 

 family all-important to the student of plant-life is that 

 of the carbo-hydrates. Here the hydrogen and the 

 oxj'gen (Lindley's Introd.) are present in the pro- 

 portion in which they form water, i.e. — 



®" 



-C'D 



H 1= 0„, or H sa O u , or 1I 1() 5 , retain the same pro- 

 portion, just double the number of H atoms compared 

 with the number of 0. 



Of these carbo-hydrates there are three groups, to 

 which are given the names glucoses, saccharons and 

 amyloids (some use glucoses, sucroses and amyloses). 

 They differ only in the relative amount of Q) — ©— (n) 

 they contain. 



Glucoses 



... C 



six 





H 



t'.yelve ... 









six 



Saccharons 



... c 



twelve 





II 



twenty- two 









eleven 



(Or some multiple of six, ten and five, as e. g., twenty-four, 

 forty and twenty ; in any case the H number is double the O.) 



Now the point here to notice is that a glucose be- 

 comes a saccharon by the addition of II two, one 

 (there is hardly space to put the requisite number 

 of circles in a column of this width), or an amy- 

 loid by the subtraction of H two, one. Slight 

 though this difference may appear to those not 

 accustomed to think of these matters, it completely 

 changes the character of the compound in many 

 respects. 



For example, every one knows the difference 

 in taste between starch, which is an amyloid, and 

 Grape sugar, which is a glucose. What Is the 

 explanation of our sensations of taste and smell 

 we do not at all know. But we possess them and 

 trust to them. Taste tells us there is some difference 

 between starch and sugar. In the process of diges- 

 tion we transform starch to sugar. 



c 



c 



c 



c 





II 



H 



H 



H 



II 















O 



o 



The " acids " which are found in various fruits have 

 a chemical relationship not far removed from one 

 another. For example, there is in Apples, Fears, and 

 Rhubarb, &c, an acid called malic— 



II 



In Grapes, Pine-apples, &c, an acid called tar- 

 taric — 



C C C C 



H H II II II II 







In Lemons, Gooseberries, Currants, &c, an acid 

 called citric — 



C C C C C C 



II II H II II H II II 

 O O O O O 



Yet a trained palate readily tells the difference in 

 flavour. The change of flavour in the ripening of 

 fruits much depends on a slight relative difference 

 of the II and present in each molecule. 



That the difference of one in a compound has in 

 some cases most important influence mav be illus- 

 trated by the difference CO and CO.. 



-We breath out C0„, candles and lamps give it off, 

 and if we sit in a badly ventilated room we feel un- 

 comfortable. But C0„ is not " poisonous " to us, 

 while CO is. A charcoal-pan in a room with no 

 ventilation has been not infrequently used as an 

 " end to the troubles of life." Again, plants can de- 

 compose C0„ but not CO. 



This apparently slight chemical difference between 

 starch and sugar is accompanied by another. Sugar 

 is soluble in cold water, starch is not. There 

 is another known difference among the carbo- 

 hydrates, to be mentioned immediately. A moment's 

 consideration of the close connection between 

 starch and sugar will show its bearings on the 

 question of tuber formation. Starch is formed in 

 the leaf, and it is a transient compound. (The 

 recent work on this subject will be spoken of later.) 

 Starch accumulates in the tuber in the form of 

 granules ; but it has been said to be not found 

 in the stem. How does it get from the leaf to the 

 stem ? 



Some cultivators and Potato dealers have spoken 

 to me incredulously about the conversion of starch 

 into sugar. I verily believe they have pictured to 

 themselves some such kind of thing as a pound of 

 starch neatly tied up to go home for stiffening frills 

 and lace, and that no " Heigh, presto ! quick, 

 change ! " could make it possible to find a pound 

 of lump sugar on undoing the parcel. At any 

 rate the notion of starch and sugar seems limited 

 to the form in which they are in the habit of seeing 

 them. 



Now it is necessary to keep in mind the difference 

 between a starch molecule, a starch cell, and a starch 

 grain or granule. 



From what has been said above about the size of 

 atoms, it will be understood that a starch molecule 

 formed of a group of atoms is utterly beyond the 

 range of vision even with our highest microscopes. 

 A vegetable cell is a visible object, and a starch 

 cell simply means one that contains starch, or in 

 which starch is being formed, not necessarily one 

 " made up " wholly of starch. Granule or grain is 

 used for the accumulated starch. W. S. M. 

 (To be continued.) 



PLANT PORTRAITS. 



Bilbekqia Bueanteana X, Andre, Ciartenjhra, 

 October. — A cross out of B. vittata by B. pallescens, 

 with oblong, obtuse, dentate leaves and pendulous 

 panicles of flowers, with oblong, crimson bracts and 

 elongate blue flowers. 



Cornus stolonifera, Revue Horticole, October 1. — 

 Leaves oblong-lanceolate, paler beneath, berries 

 blue. 



Mesospinidium vulcanicum, Bevuede V Horticulture 

 Beige, October. 



HAMPSHIRE FIELD CLUB 

 FUNGUS FORAY. 

 The expanse of the New Forest is almost unknown 

 to the predacious fungus hunter ; until very lately it 

 has never been thought about, and now the one 

 element wanting is a local enthusiast who will set 

 himself to work in good earnest to ascertain what 

 treasures of fungi the New Forest region will furnish. 

 It is all very well to have a day or two set apart once 

 a year, and to invite down a few of those who love 

 the sport, for a fungus hunt, but all the rest of the 

 year is forgotten, and in this way the fungi of t!,e 

 Forest will not be explored till Doomsday. What a 

 glorious spot for anyone devoted to the study to 

 settle down upon in August, and keep it up till 

 October, hunting in all directions day by day, over 

 miles of wooded country, genuine forest and planta- 

 tion, sketching away all the juicy days, and tramp- 

 ing all the dry ones ! And what a budget of treasures 

 he might hope, to find for the delectation and 

 astonishment of those who consume the autumn 

 lolling on the beach, and throwing pebbles in the 

 sea. Last year the Hampshire Field Club, at the 

 instigation of the Rev. W. L. Eyre, of Swarrator, 

 made their first effort at organising a fungus excur- 

 sion in the Forest, and this year it was repeated, with 

 still greater success. Although the crop of fungi 

 was far richer than in the Forest of Dean, it was by 

 no means equal to what it has been in some previous 

 years, whilst better than last year. In 1887 only 

 abaut 10(j species were collected and recorded 

 during the two days, but in 1888 no less than 

 171 species were determined, and of these 

 sixty-eight species found last year were found 

 again this year, whilst thirty-eight of those found 

 last year were not seen this year at all. The 

 first day's excursion (on Thursday, October 11), 

 was made in Boldrewood, and Knightwood, or on 

 the way thither, the Rev. W. L. Lyre and M. C. 

 Cooke undertaking the determination and record of 

 the species. The majority of the excursionists wtre 

 interested chiefly in the esculent qualities of the 

 " Toadstools " found. Not a Mushroom was seen, and 

 all the specimens of Lactarius deliciosus were 

 shrivelled and dried up, but Hydnum repandum was 

 plentiful, and there were a few of the Chantarelle. 

 Some of the most interesting to the novices were 

 two or three large clumps of Polyporus imbricatus, 

 the little Hydnum auriscalpium in profusion, the 

 jelly-like Tremellodon gelatinosum, the Club of 

 Hercules, Clavaria pistiilaris, very large tufts of 

 Clavaria aurea, Cortinarius sanguineus, and the 

 delicate Cortinarius albo - violaceus ; Lactarius 

 cyathula, a rare species, fouhd under Birch trees; 

 and a very great quantity of very fine specimens of 

 Agaricus (Tricholoma) imbricatus.. At the close of 

 the day the party returned to Southampton, when a 

 meeting was held in the evening at the Hartley In- 

 stitution, and the specimeus collected during the 

 day were displayed on the tables, and for about an 

 hour Dr. M. C. Cooke demonstrated to the audience 

 chiefly from the edible and poisonous species on the 

 tables. The following day (Friday) was again devoted 

 to the Forest, starting on foot from the Lyndhurst 

 Road Station, through an enclosure, and thence fol- 

 lowing a stream towards Minstead. About fifty 

 additional species were found on the second day, 

 together with many of those recorded on the first. 

 The first hour or two were spent in Fir plantations, 

 where the species were comparatively few in number, 

 but the individuals were numerous ; Russula expal- 

 lens everywhere, but it seems doubtful whether it is 

 any more than a variety of the sulphur-gilled Rus- 

 sula drimeia. It was here that the Tremellodon 

 gelatinosum was found. Dr. Quelet recommends 

 this species as delicious if eaten raw, with a litt'e 

 sherry, after the manner of calf's foot jelly. Two 

 or three specimens of Coprinus picaceus were col- 

 lected during the two days, dripping with inky juice, 

 and this led to the discussion of the proposal which 

 has been made for the printing of bank-notes with 

 the juice of Coprinus, that fluid consisting of spores 

 of a definite size and form, can at any time be 



