42 MR. SOLLY ON THE POTATO MURRAIN. 



me, as observed by Lord Plill and Sir J. Lubbock. In both of 

 these, potatoes of 1844, under cover, had sprouted and formed 

 young tubers, which, tliough never exposed to the air or wea- 

 ther, were found affected by the rot. I believe, however, that 

 in these two cases, the disease was not the true rot, but a modi- 

 fication of the dry rot, which has been long known as sometimes 

 occurring in potatoes. 



In conclusion, I believe the potato disease was caused by a 

 peculiar combination of atmo.spheric conditions, which, by sud- 

 denly checking the rapid growth of the plants, led to the presence 

 of partly decomposed azotised matter in the lower part of the 

 stem ; this matter being carried through the structure of the 

 plant at a period when there was little light, and consequently 

 when the formation of organic matter was j)roceeding but slowly, 

 communicated its own state by a process of fermentation, to va- 

 rious parts of the plant, and thus originated the evil ; tlie increase 

 of which was assisted by the abundance of moisture and the de- 

 ficiency of light. If this view be correct, it is evident that the 

 recurrence of such an effect in succeeding years is liigldy impro- 

 bable, though of course at all times possible ; depending on a 

 singular combination of atmospheric phenomena, and liable to 

 be produced whenever they again occur ; but not to be expected 

 as a permanent consequence of this year's disease. 



IV. — Memoranda relating to the Cultivation of 3lelons. By 

 John Williams, Esq., C.M.H.S. ' 



(Communicated with a Green fleshed Mc4on, ■weighing 2 lbs. 1 1 oz., and 

 a Cabul Melon, weighing 2 lbs. 5 oz. Oct. 14, 1845.) 



I have desired my gardener to send up a melon or two ripened 

 in my frame, the south end of which is open to the outward air 

 night and day, except that it has some fly-wire screen, the wires 

 being very close together and painted black. This wire screen, 

 standing as it does in the continued inclination of the roof, of 

 course presents a metallic surface of black wire, and, say in sum- 

 mer time from 10 a. m. till 3 p. m., receives the rays of the sun ; 

 the wire is tiien heated say fi'om 80' to lOO"*, and consequently 

 heats the air which passes through the interstices of wire, and 

 I always find the thermometer placed under the shade of the 

 melon leaves standing at 80' or 85'' ; if a very hot day at 90°. The 

 upper ends of the glass frame which forms the north side are 

 raised by wedges according to the weather, from an incli to two 



