O'aly 15, 1875. ] 



JOURNAL OF HORTICULTURE AND COTTAGE GARDENEK. 



49 



addition to our knowledge of Peronospora infestane, to which 

 fungus I had no doubt from the beginning that the threads be- 

 longed, I kept it under close observation, and in about ten days 

 the mycelium produced a tolerably abundant crop, especially in 

 the abortive tubers of the two-sized bodies I had previously 

 seen and measured in the fresh leaves. The reason why these 

 objects, which undoubtedly occur in and about the spots, are so 

 extremely few in number in those positions is, I imagiue, be- 

 cause they require a different set of conditions for their normal 

 growth, and these conditions are found in abundant and con- 

 tinued moisture. 



The larger of these bodies, the measurements of which I shall 

 give, with a woodcut illustration, in an early number of the 

 Gardeners' Chronicle, I am disposed to consider the "oospore" 

 of the Potato fungus, and the smaller bodies I look upon as the 

 "antheridia" of the same fungus, which are often terminal in 

 position. The filaments of the latter are commonly much arti- 

 culated, and sometimes more or less moniliform or necklace- 

 like. Both oospore and antheridium are very similar in nature 

 and size to those described as belonging to Peronospora alsi- 

 nearum and P. umbelliferum, and this is another reason (beyond 

 my seeing undoubted P. infestans on Potato leaves at the be- 

 ginning of June) why I am disposed to look upon these bodies 

 as the oospore and antheridium of the Potato fungus. 



The larger bodies are at iirst transparent, thin, pale brown, 

 furnished with a thick dark outer wall, and filled with granules ; 

 at length a number (usually three) of vacuities or nuclei appear. 

 The smaller bodies are darker in colour, and the external coat 

 is marked with a few reticulations, possibly owing to the col- 

 lapsing of the outer wall. At present I have been unable to 

 detect any fecundating tube (described as belonging to the 

 antheridium of other species of Peronospora), but I have ob- 

 served the two bodies in contact in several instances. After 

 fertilisation has taken place the outer coat of the oospore en- 

 larges, and appears to be cast off. Both antheridium and rest- 

 ing-spore are so slightly articulated to the threads on which 

 they are borne, that they are detached by the slightest touch, 

 but with a little care it is not really difficult to see both bodies 

 in situ, and my observations lead me to think that conjugation 

 frequently takes place after both organs are quite free. The 

 antheridia and oospores are best seen in the wettest and most 

 thoroughly decomposed portions of the tissue of the decom- 

 posing tuber, but they occur also in both the stem and leaf. I 

 consider Mr. Alexander Dean's remark, as reported in Gar- 

 deners' Chronicle for June 19th last, page 79.3, to have a distinct 

 bearing on this point, where he says, " In all cases where the 

 seed tubers were cut they were quite rotten.'' 



Before I referred to De Bary's measurements of similar organs 

 in otlier species of Peronospora I was disappointed with the 

 results of my observations, and felt disposed to refer the bodies 

 and threads in the Potato leaves to Saprolegnia, but a glance at 

 the figures which I shall shortly publish, and the similar figures 

 copied from De Bary to the same scale, will show that if the 

 bodies observed by me are Saprolegnia-like, the oospores and 

 antheridia figured by De Bary show an exactly similar alliance. 

 Still, as the Saprolegniese are at present defined, I am by no 

 means inclined to describe the bodies observed by me as really 

 belonging to that tribe of plants. 



The Saprolegnieas have the habit of moulds and the fructifica- 

 tion of AlgfE, and they live on organic matter, animal and vege- 

 table, in a state of putrefaction in water. One of the best known 

 of these plants is Botrytis Bassiana, the parasite which causes 

 the disease of silkworms. Now the genus Botrytis amongst 

 fungi is almost or quite the same with Peronospora, to which 

 the Potato disease belongs ; and I consider it a strong argument 

 in favour of my Saprolegnia-like bodies being the oospores and 

 antheridia of the Peronospora when such an authority as Mr. 

 Berkeley (" Micrographio Dictionary," p. C) considers one of the 

 Saprolegnieas (Achlya) "may be an aquatic form of Botrytis 

 Bassiana " — the silkworm disease. 



The common fungus which attacks fiies (so frequently seen on 

 our window-panes in autumn), Sporendonema muscos, Fr,, is 

 said to be a terrestrial condition of Saprolegnia ferax, Kutz., 

 which latter only grows in water ; and if a fly infected with the 

 fungus be submerged the growth of the Saprolegnia is the 

 result. It would now seem to be somewhat the same with the 

 Potato when diseased, in the fact that when submerged a second 

 form of fruit is produced. 



Between the two moulds Botrytis and Peronospora there is 

 little or no difference ; the characters of Corda, founded upon 

 the continuous or articulate filaments, cannot be relied upon, 

 and even De Bary himself figures P. infestans with articulate 

 filaments Like a true Botrytis. The intimate connection, how- 

 ever, between the Saprolegnieae and some moulds cannot be 

 denied, as the instances above cited clearly show ; and I am 

 therefore disposed to think that the fungus which produces the 

 Potato disease is aquatic in one stage of its existence, and in 

 that stage the resting-spores are formed. 



Reference should here be made to the bodies found germinat- 

 ing in the intercellular passages of spent Potatoes by Dr. Mon- 



tague (Artotrogus), and referred by Mr. Berkeley to the Sepe- 

 douiei. Ever since Mr. Berkeley first saw these bodies he has 

 had an unswerving faith in the probability of their being the 

 secondary form of fruit of Peronospora infestans, but, unfor- 

 tunately, as far as I know, no one has ever found a specimen of 

 Artotrogus since Montagne. 



The question may, therefore, be naturally asked in conclusion 

 —How does Artotrogus agree with the presumed resting-spores 

 here figured and described ? And has Mr. Berkeley been right 

 or wrong in clinging so tenaciously to his first idea ? Fortunately 

 for the investigation of the Potato disease (which can never be 

 cured till it is understood), Mr. Berkeley has given in thfi Journal 

 of the Royal Horlicultiiral Societij the number of diameters 

 his figures are magnified to, and I have here farther enlarged 

 those figures so as to correspond in scale with my own drawings, 

 which latter are sketched with a camera lucida. It will be seen 

 that they are the same with each other both in size ami habit, 

 with the exception of the processes on the mature spore of 

 Artotrogus — which processes may possibly be mere mycelial 

 threads, or due to the collapsing of the inflated epispore. The 

 reason these resting-spores have evaded previous search is that 

 no one has thought of finding them amongst leaves which had 

 been macerated for a long period in water. There is, however, 

 nothing unreasonable in fruit being perfected in water or very 

 damp places, as it is common in the Saprolegniete, and amongst 

 Algse in general. To sum up, there are four reasons why the 

 bodies here described belong to the old Potato disease : — 



1. Because they are found associated with the Peronospora 

 and upon the Potato plant itself. 



2. ISecause they agree in size and character with the known 

 resting-spores of other species of Peronospora. 



3. Because some other moulds are aquatic in one stage of 

 their existence. 



i. Because they agree in size with Artotrogus. 



I will only say in conclusion that it affords me great pleasure 

 to lay these additional notes on the Potato disease before the 

 Society which thirty years ago published Mr. Berkeley's original 

 and excellent memoir on the same subject. 



THE QUALITY OF PEAS. 



How is it that with a fine Pea season like the present one, 

 and the market overflowing, and hard small Peas almost going 

 a-begging, that it is so difficult to purchase a dish of reaUy 

 delicious Peas ? Is it that raisers of Peas are paying too much 

 regard to mere colour of pod and size ? Colour is very tempt- 

 ing, and growers like to treat the public to a deep green-podded 

 Pea ; but such are not the best. Prizetaker, for instance, is 

 fine to look at, but not good to eat. 



When varieties of Peas were less numerous the market quality 

 was better than now. Where is the old Early May ? None of 

 the early round Peas are equal to it, and none of them a week 

 earlier. When that. Champion of England, and Hair's Dwarf 

 Marrow were the staple sorts, we were certain of good Peas at 

 every dealer's, but it is not so now. Such Peas always com- 

 manded a sale, and in my opinion would do so now. 



Being neither a grower nor a seller, but a consumer, I am, 

 perhaps, somewhat behind the fashion of the day in asking, 

 not for grand Peas to look at, but sweet and delicious Peas to 

 eat. Am I singular and alone ?— A City Man. 



FICUS BEPENS MINIMUS. 

 Foe clothing the wall of a stove or intermediate house with 

 close green foliage the above plant is particularly suitable. 

 It is brighter in colour than P. repens, and its foliage is not 

 more than half the size of the old species, the separate leaves 

 not being more than a quarter to half an inch in diameter. It 

 is impossible to imagine anything clinging more closely to a 

 wall than does this plant ; in fact, it covers completely any 

 surface and still takes up scarcely any room. It clings with 

 the persistency of Ivy, and yet does not project from the wall 

 half an inch. I saw it the other day in Mr. Kinghorn's nursery 

 at East Sheen, covering the brickwork of the ends of a plant 

 stove. For rockeries under glass, or the covering of walls of 

 any kind, this plant is pre-eminently suitable, and can be 

 turned to good account in surfacing knolls, boulders, and other 

 adjuncts of the fernery. It will possibly flourish in a green- 

 house temperature, for we observed where the plant had pushed 

 itself through the seams of the brickwork that it was as healthy 

 on the outer wall as within the house, but that of course was 

 only the growth of the current summer. This is a distinct 

 plant for a distinct purpose, and for that purpose— the impart- 

 ing to surfaces a living green covering as close as if glued 

 there— it is unequalled. Those seeking for a carpet plant to 

 completely hide bare walls or other surfaces, and which re- 



