Itetrospective Criticism. Queries and Aiis'ucers. 61 



the having at all times an atmosphere saturated with moisture. A number of 

 members spoke on the subject ; but the ideas were little different from those 

 suggested when the subject of propagation was before the Society. 



Jult/ 10. — Mr. Fish introduced the subject of the cultivation of the mush- 

 room. An animated discussion took place, but no great diversity of opinion 

 was elicited. For producing spawn, Mr. Fish recommended a mixture of 

 horse and cow-dung. In forming his beds, he uses the dung from old linings, 

 or any litter rather dry than otherwise, capable of raising a little heat ; spawns 

 the bed when milkwarm ; and, when there is no danger from over-heating, 

 covers it with a casing of cow-dung in a wet state, or fresh horse-dung if cow- 

 dung is not to be had; the use of which is to give strength to the mushroom 

 before coming through the mould, and to render it thick and fleshy. He then 

 covers the beds with H in. of mould, rather stiiF than otherwise, beating it 

 firmly, and attaching great importance to earthing up as soon as possible after 

 spawning. In beds out of doors, liable to get wet before they are spawned, 

 the spawn is wrapped into a good handful of dry litter, and then firmly in- 

 serted into the beds; when the wet dung, by which it is surrounded, will 

 operate in the same manner as a casing of cow-dung under cover. In beds put 

 up out of doors without prop covering, especially in the winter months, care 

 must be taken that they be not too hot when spawned : it is better to have 

 them rather cool ; as, if a sufficiency of heat does not arise after being earthed 

 up, a proper temperature can at any time be infused and kept up by means of 

 covering with straw and dung. Mr. Judd recommended watering with lime- 

 water to destroy worms and woodlice ; but doubts were expressed if the 

 using of lime, so fresh as to destroy the insects, would not also be prejudicial 

 to the mushroom. The growing of mushrooms in summer was much discussed ; 

 and it was agreed that, unless there was the command of cool sheds or cellars, 

 the growing of them was almost labour thrown away, especially out of doors ; 

 as much watering would be required to keep the beds cool by evaporation. 

 The temperature of 60'^ was considered most favourable to the growth of the 

 mushroom. 



Art. V. Retrospective Criticism. 



A DOUBLE-FLOWERED Rhododendron. — I observe, in Vol. XIII. p. 537., you 

 state that "a double-flowered rhododendron has been originated in Paris recently, 

 and the whole stock imported into this country by Mr. Lawson of Edinburgh." 

 May I be permitted to inform your readers that I have cultivated a double- 

 flowered i?hododendron ponticum for the last ten years or upwards ? I pur- 

 chased my original plant from Messrs. Loddigcs, who, I believe, had had it 

 some years ; but how or where it originated I am not aware. Whether the 

 Paris plants are of the same species, or of some other, I, of course, am igno- 

 rant; but I am aware that it frequently happens that plants are sent to 

 this country from the Continent, as novelties, which have originally been sent 

 hence to the Continental gardens. — J. Cree. Addlestone Nurserj/, Z)ecA837. 



The variety alluded to by Mr. Cree was published in the Hortiis Britaji- 

 nlciis (p. 171.) in 1830; that purchased by Mr. Lawson was found in a bed of 

 seedlings in Cel's nursery, Paris, in 1832 ; it is called i?hododendron pon- 

 ticum liyacmthifldriim. (See Annates de Flore, &c., September, 1836.) The 

 flowers are very numerous ; each consisting of fifteen or sixteen petals, of a 

 fine violet rose colour. Leaves as in the species. — L. L. L., Paris, Decem- 

 ber 2\. 1837; and Cond. 



Art. VI. Queries and Anstvers. 

 An Insect on Tropce^olum peregrhncm. — An insect has troubled us much 

 here this season, by injuring the leaves of Tropae^olum peregrinum. The corn- 



