184 



THE GARDENERS' CHRONICLE. 



[August 18, 1888. 



with grand specimen Camellias, Azaleas, Tree Ferns, 

 and miscellaneous greenhouse plants. 



It is in contemplation to remodel and extend the 

 glass on a scale proportionate with the splendid 

 style of the new mansion. The grounds also will be 

 remodelled and improved in harmony with the 

 .•character of the same, and hardly a finer field could 

 >oe found for the display of taste and skill in land- 

 -3cape gardening. A curious object in one portion of 

 ■the grounds is a fac-simile of the hut in which Dr. 

 Livingstone died. The late proprietor of Kelly 

 House was a personal friend of the great African 

 missionary and explorer, and had Chumah and Susi, 

 two of the Doctor's attendants who were with him 

 svhen he died, some time at Kelly, and employed 

 <them to build the primitive-looking hut, which is as 

 much cherished by Mr. Stephen as by his predecessor 

 in possession of the estate. W. S. 



DISEASE OF LILIES. 



PeBONOSPOEA ELLIPTICA. 



In the Gardeners' Chronicle for September 10, 

 1881, p. 340, will be found an illustration and 

 description of a fungus there first illustrated and 

 ■described by the Eev. M. J. Berkeley under the 

 ■name of Ovularia elliptica. Seven years have passed 

 since this description was written, and I doubt 

 .whether any observer other than myself has since 

 .seen Ovularia elliptica in good form. In ninety-nine 

 cases out of a hundred the perfect fungus is not seen 

 on Lilies dying from the disease, and no trace of it 

 is to be seen on Mr. Berkeley's original examples 

 •now at Kew ; in fact it is probable that Mr. Berkeley 

 'himself only saw the fungus in an imperfect state. 

 No one has said anything new about the fungus 

 ■since the original description was published, and if 

 any one had ventured to " confirm the Ovularia " it 

 would have been a proof that the " confirmer " had 

 aiever seen it. I have several times seen the conidia 

 or spores upon Lilies, and frequently a mycelium 

 which appeared probably to belong to the the fungus. 

 The Lily fungus, as far as my experience goes, does 

 mot generally emerge from the stomata, but it usually 

 >vegetates as mycelium only within the living 

 leaves and stems. This mycelium grows with 

 such extraordinary rapidity that it will completely 

 destroy a bed of apparently healthy Lilies in a day 

 or two. The Lily stems are left like dead brown 

 sticks, and the leaves hang round the withered dis- 

 coloured stems like fragments of ragged, brown, sod- 

 dened tissue-paper. The ravages of the fungus are 

 mot confined to the open air, for I have seen its effect 

 upon Lilium auratum in greenhouses, but it perhaps 

 preys with the most deadly effect upon L. candidum. 

 Various other Lilies are also attacked, and it is pro- 

 bable that no species can withstand the contact of 

 the fungus. It has been seen on L. superbum, L. 

 •chalcedonicum, L. pardalinnm and others. My 

 neighbours have (happily !) had their Lilies destroyed 

 fby wholesale this summer, so that I have had a good 

 ■opportunity of studying the fungus. I have also 

 tteen able to produce it in a perfect state by culture, 

 and so to spread it j udiciously amongst selected plants. 

 As the fungus seldom produces spores naturally, the 

 mycelium of the fungus is necessarily confined to the 

 interior party of the attacked plants, and this habit 

 .of the fungus is not favourable to spreading from one 

 plant to another. 



The Lily fungus maybe artificially made to perfect 

 atself by cutting a fungus-infested Lily stem in two, 

 whilst the Lily is still in the ground. After a single 

 warm humid night the transverse cut across the 

 stem will exhibit a perfect miniature forest of the 

 so-called Ovularia elliptica. Cutting or breaking off 

 the stems of dressed plants therefore greatly aids 

 the spread of the fungus. Now if circumstances have 

 been fairly favourable the fungus growth from the 

 transverse cutting when placed under the microscope, 

 will be seen something like fig. 21, enlarged 

 400 diameters. The fungus will now be seen to 

 belong less to Ovularia than to Peronospora, and 

 ih« parasite may be known as Peronospora elliptica. 



The fungus is sometimes much more branched than 

 shown in the illustration, and the branches are 

 often much longer, but I have engraved the special 

 specimen on fig. 21 for the reason that I fortu- 

 nately have the actual example preserved 

 on a glass slide, with all the conidia or 

 spores in situ. The illustration shows a 

 single thread emerging from the transversely cut 

 cells of a Lily stem. Now it often happens 

 that the branches of the Peronospora get broken off 

 and are seen free as at a, and it must have been from 

 branches like these that Mr. Berkely reasonably 

 described his fungus as an Ovularia. The growth 

 seen at a is nothing but a lateral branch broken 

 from a long stem. It agrees very well with Mr. 

 Berkeley's original illustration in the number of the 

 Gardeners' Chronicle above quoted. The spores 

 readily germinate in water or on any damp surface ; 



Fie. 21.— PERONOSPOKA ELLIPTICA : THE LILY EUXGUS. 



certain of the spores produce a convolute mass of 

 mycelium as at n, which, on the opening of the spore, 

 protrudes as a germinal thread ; other spores or 

 conidia produce zoospores, as at c. When the 

 zoospores are mature the large mother spore opens 

 and the zoospores sail away, exactly as in the case 

 of the Potato fungus, Peronospora infestans. On 

 coming to rest the zoospores in turn open and pro- 

 duce a germinal thread. 



The resting-spores which the fungus, no doubt, 

 produces, have not yet come to hand ; this is pro- 

 bably owing to the retiring nature of the fungus 

 itself, which requires, as I have shown, a little judi- 

 cious coaxing to exhibit itself in good form. Mr. 

 Berkeley gave no scale to his little drawing in the 

 Gardeners' Chronicle, neither did he mention the 

 size of the large conidia ; he, however, afterwards 

 supplied this omission in the pages of the Annals of 

 Natural History. The spores shown in fig. 21 agree 

 exactly with the size given by Mr. Berkeley. As 

 soon as the Peronospora has run its course, and 

 directly the affected material approaches decay, 



another fungus grows on the surface of the leaves 

 and stem, and hastens putrescence ; this is Polyactis 

 vulgaris, illustrated and described in the Gardeners' 

 Chronicle for February 6, 1886, p. 173. A reference 

 to this illustration will show a remarkable similarity 

 between it and the plant before us, but the fungus 

 upon Lilies is different, and enormously larger in all 

 its parts. Polyactis cana, a species allied to P. vul- 

 garis, has large oval spores, but it seems impossible 

 that P. cana could have been mistaken for Ovularia 

 by Mr. Berkeley, for Mr. Berkeley was the original 

 describer of P. cana. The habit of the fungus on 

 Lilies seems totally different from Polyactis, which 

 should invariably grow on plants already rotting ; 

 the habit of the Lily fungus, on the other hand, is 

 entirely that of Peronospora. The habit of the 

 Peronospora of Lilies is considerably like that of 

 Peronospora interstitialis of Primulas (see illus- 

 tration in Gardeners' Chronicle, May 1, 1886, fig. 

 124, p. 564), but whatever decision may be come to 

 as to the name of the fungus of Lilies, the illustra- 

 tion published herewith gives the first exact repre- 

 sentation of it. 



Hyacinths, Tulips, and other liliaceous plants are 

 probably sometimes destroyed by the fungus here 

 named Peronospora elliptica. 



In the now familiar scourge of Lilies we seem to 

 have a close ally of the Potato fungus, and one 

 equally difficult to get quit of, as all the involved 

 features of the cause of one disase are repeated in 

 the other. If all infested and dying material is 

 destroyed, it may prevent an attack another year ; 

 but unless all Lily growers act in concert, one per- 

 son's unburnt plants may infect a neighbour's garden, 

 where all diseased material bad been carefully buint 

 or otherwise destroyed. Worthington G. Smith, 

 Dunstable. [We may shortly look for the publication 

 of an important series of observations on this 

 fungus by Professor Marshall Ward. Ed.] 



THE CHEMISTRY OF VEGETA- 

 TION, IN REFERENCE TO THE 

 GROWTH OF THE POTATO. 



(Continued from p. 151 J 



Atomic Weights and Symbols. 



Though out of historical order, it is closely con- 

 nected with this part of the subject to give here the 

 symbols and atomic weights now adopted of some of 

 the elements with which plant study brings us in 

 contact. 



Quite as an arbitrary matter, on account of its 

 lightness, the gas hydrogen, H, was taken as a standard 

 of weight, j ust as we have an arbitrary yard or an 

 arbitrary pound. II being taken as unity — 1, we 

 have now the weights as follows : — = 16, C = 12, 

 N = 14. P (phosphorus) = 31, Ca (calcium, 

 commonly known when combined with as 

 lime) = 40 ; CI (chlorine), 35'5 ; Na (natron or 

 sodium), 23 ; K (kalium or potassium) 391. 



When a chemist writes, in what is called a 

 formula, CO or Ca, he does not mean any in- 

 definite quantity or weight, but the weight in 

 which the element combines.* The atomic weight 

 is implied in the symbol. The proportions in 

 which combinations take place are indicated by 

 numerals which it has become customary (though in 

 early chemical papers it was not so) to put after the 

 symbol and below the line. For example, the series 

 of combinations of nitrogen and oxygen mentioned 

 above might be written N„ O, N„ 2 , N„ 3 , N 2 O t , 

 N 3 5 .* In the first there are 28 parts by weight of 

 nitrogen to 16 parts by weight of oxygen, and in the 

 last, 28 of nitrogen to 80 of oxygen (5 times 16 equal 

 80). On the atomic theory, this means that two atoms 

 of nitrogen having together a weight of 28, 14 each, 

 relative to the standard weight atom of hydrogen 

 (taken as 1) combine here with five atoms of oxygen, 

 having each a weight of 16 relative to the weight of 

 an atom of hydrogen. As all analyses are based on 

 what the balance tells us, it is important to have 

 a clear idea of bow the chemist records his results. 



* It -would make this papttr too long to enter into the much- 

 discussed question, whether what we call elements are really so. 

 t N 3 3 and N„ O, arc relatively the same as N" and SO.. 



