32 



JOUBNAL OP HOBTICULTUKE AND COTTAGE GABDENEE. 



[ July 11, 1872. 



phide of silver, and it has been inferred therefrom that sulphur 

 vaporises at ordinary temperatures ; and the theory has been 

 advanced by a "well-known vegetable physiologist, that the 

 oxygen given off by the leaves of plants to which sulphur has 

 been applied, oxidises it and produces sulphurous acid, and thus 

 the action of sulphur in destroying vegetable organisms may be 

 accounted for. But this theory is not borne out by my experi- 

 ments. When silver leaf is suspended over pure sulphur it does 

 not tarnish more rapidly than when suspended in the air, and 

 its conversion into the sulphide by the roll sulphur may be ex- 

 plained by the fact that that substance contains free sulphurous 

 and hyposulphurous acids, and sulphureted hydrogen, which 

 are constantly escaping from it. "When pure sulphur is applied 

 to the leaves of plants no evidence of oxidation can be detected 

 by either litnius, or starch and iodine paper. If oxidation were 

 to take place under such circumstances, the product, if sul- 

 phurous acid in the first instance, would be immediately con- 

 certed into sulphuric acid by further oxidation, and it could not 

 escape detection. Further, precipitated sulphur, beingin a much 

 finer state of division than sublimed sulphur, would be more 

 easily oxidised, and ought to prove the more potent agent ; but 

 practically it is found to be the least so. 



Sulphur in various forms is used by medical men and veteri- 

 nary surgeons for the destruction of the itch and other insects, 

 and in the treatment of various diseases (as ringworm), caused, 

 or accompanied by fungus growth infesting the skin and hair of 

 men and animals ; but sulphurous acid, in solution, is in many 

 instances substituted for them on account of its more certain 

 action. Many surgeons, indeed, believe that the beneficial 

 action of sulphur ointment in the treatment of itch is to be at- 

 tributed to the grease of which it is made, rather than to the 

 sulphur it contains, and this is probably time, as the quantity of 

 sulphurous acid is exceedingly small, and I find the action of the 

 ointment is remarkably increased when the sulphur has been 

 strongly impregnated with acid previous to being made into 

 ointment, and this is equally true of its other applications in 

 medicine. 



In addition to its destructive action on organised bodies, sul- 

 phurous acid possesses a powerful chemical action on the organic 

 and inorganic products of decomposing animal and vegetable sub- 

 stances, and the emanations from persons and animals suffering 

 from infectious diseases ; hence it is one of the most potent and 

 valuable disinfectants we possess, and it appears to prevent the 

 spread of small-pox, diphtheria, cattle plague, &c. Its qualities 

 as a deodoriser are also very considerable. It attacks and 

 destroys sulphureted hydrogen, and neutralises the strong 

 smell of ammonia and other alkaline bases, but without losing 

 its antiseptic properties or destroying their manurial value. — 

 (Crookes.) 



From my experiments and observations, and from the well- 

 known properties of sulphurous acid, I conclude, therefore, that 

 it is the acid, accidentally present in the sulphur, which is the 

 active agent in the destruction of mildews and blights, and that 

 the sulphur is only the medium for its application. This is a 

 fact, not only of scientific interest, but of great practical and 

 commercial importance, for under the mistaken impression that 

 the sulphur itself is the active agent, great care and expense 

 have been incurred to secure its freedom frorn acidity, which is 

 by no means necessary. 



Sulphur, like charcoal and many other substances, possesses 

 the power of absorbing a large quantity of sulphurous acid, and 

 by a modification in the refining process the acidity may be con- 

 siderably increased, and the quantity of sulphur correspondingly 

 diminished, and a more certain and uniform agent produced. 

 For horticultural purposes, however, it is necessary to limit the 

 quantity of sulphurous acid, or it will prove destructive to the 

 plant as well as the parasite. This limit I have established 

 practically by experiments made on Eose trees infested with 

 mildew, and as the Eose mildew is with difficulty destroyed by 

 common sulphur, except by repeated applications, this prepara- 

 tion (to which I have given the name of sulphozone, for reasons 

 given above), may be considered to be of the maximum strength, 

 and four or five times stronger and more potent than sublimed 

 sulphur. In substituting it, therefore, for sulphur, a great saving 

 will be effected in the cost of sulphur, its carriage, and the time 

 and labour of applying it. There will, moreover, be the ad- 

 ditional advantage of not loading the f oliage with a large quantity 

 of sulphur powder, which must in some measure impair its 

 health by its mere mechanical presence, and in the case of Hops, 

 the brewers will have less ground for objecting to the quality of 

 the produce. Sulphozone, being a fine dry powder like sulphur, 

 may be applied in a similar manner, and with the same appa- 

 ratus, care being taken to use a much smaller quantity — i.e., 

 about a quarter of that of sulphur. 



For medical, veterinary, and sanitary purposes, a very strong 

 sulphozone has been prepared to take the place of sulphur in the 

 officinal preparation, and for use as a disinfecting powder. This 

 substance is' exceedingly destructive to organic life, and is not 

 adapted for horticultural purposes except for dressing the stems 

 and branches of deciduous trees in the winter, and or destroy- 



ing insects where it can exert no deleterious influence on sur- 

 rounding vegetation, or for disinfecting and deodorising manure- 

 heaps, &c, for which purpose it is better adapted than any other 

 disinfecting powder, as the sulphurous acid fixes the ammonia — 

 the most valuable constituent of manure — and makes it available 

 for gardening and farming purposes, while chlorine and other 

 disinfectants destroy it, and reduce the value of the manure in 

 proportion to the extent of their action in deodorising it. 



On the conclusion of Mr. Eoberts' paper, Dr. Denny said he 

 would like to see carbolic acid tried for the purposes mentioned. 

 Mr. Murray thought mildew was a consequence of the death of 

 the plant, and not the cause of the death. 



Professor Dyer remarked that chemists doubted the possibility 

 of sublimed sulphur undergoing oxidation at ordinary tempera- 

 tures, and he agreed with Mr. Eoberts in attributing the utility 

 of sulphur to the presence of sulphurous acid. 



THE RELATIVE INFLUENCE OF PARENTAGE LN FLOWERING 

 ' PLANTS. 

 By J. Denny, M.D. 

 One of the chief objects of my paper is to urge the study of a 

 subject full of scientific interest, and of the greatest importance 

 to the practical horticulturist, but which for the want of the 

 accumulation of data derived from accurate experiments, at the 

 present is involved in much obscurity. 



If we could by the observation of results acquired through 

 the medium of a series of carefully performed experiments in 

 artificial fertilisation, obtain any reliable evidence indicative of 

 the relative influence the male (or pollen) and the female (or 

 seed) parents bear in the production of their progeny, it would 

 assist us immensely in carrying out our own designs for the 

 improvement in the form and colour of our flowers, and the 

 quality of our fruits and vegetables. 



If, for instance, we knew that either parent, and which, was 

 prepotent in conveying to its offspring certain qualities, say of 

 flavour and aroma, or of size and form, or of quality as regards 

 the texture of our fruits ; of colour, perfume, form, substance, 

 and the various qualities we may wish to perpetuate or modify 

 in our flowers, we should be able to form some proximate idea, 

 a priori, of the result that would follow our fertilisations. 



A knowledge, too, of the ancestry of the varieties we purpose 

 employing would also be desirable, to enable us to make allow- 

 ances for the modifications likely to ensue from the tendency to 

 reversion towards an ancestral type — a propensity which seems 

 to be inherent in all plants that have been much changed from 

 their original state by artificial breeding. 



It would also be a matter of scientific interest, as well as of 

 practical importance, perhaps, to know if the proportionate 

 influence borne by the respective parents in crossing varieties 

 is the same as in crossing species ? 



Whether, as the admission of fecundation is no test of the 

 plants employed belonging to the same species, we have any 

 well-defined hue of demarcation or practical test by which we 

 can distinguish between species and varieties, so that we may 

 know when to employ correctly the term hybridisation, and 

 when cross-breeding ? 



Whether there exists any real difference in the powers or 

 qualify of the pollen of the long and short stamens from which 

 we may expect to derive any specific effect on the progeny by 

 the exclusive employment of the one or the other, or to succeed 

 more readily in effecting difficult crosses ? 



Whether certain states of the atmosphere, and, if so, what 

 apparent conditions of it, favour fecundation ? 



Whether any clue can be obtained, or suggestions offered, to 

 account for the antipathies that are found to exist between 

 apparent varieties, as well as affinities between what are con- 

 sidered by botanists to be distinct species, precluding fertilisa- 

 tion in the former, and rendering it easy in the latter ? 



These are a few of the most important points that are con- 

 stantly occurring to the practical horticulturist. To how many 

 of them does our knowledge admit of a satisfactory reply being 

 given ? 



There are, doubtless, many present whose vast practical ex- 

 perience in the artificial fertilisation of our fruits, flowers, and 

 shrubs would enable them to give most valuable information 

 upon most of these points ; and as the purport of this meeting, 

 I take it, is intended to be for the genial discussion and for the 

 interchange of knowledge and ideas, I trust to the generosity of 

 those who are able to assist me in making the subject I have 

 ventured to broach interesting by throwing more general light 

 upon it than my circumscribed experience will afford. 



From early youth I have taken much interest in artificial fer- 

 tilisation, but kept no registered account of my crosses, or their 

 results, until the controversy arose respecting the tricolored 

 Pelargoniums, as to whether their leaf-markings could be repro- 

 duced by fertilisation and seed, or whether they were sports 

 only, and owing to a diseased condition of the plant. 



To ascertain for my own satisfaction the correct theory upon 

 these points, as well as with the object of obtaining, if possible, 



