HARDWICKE'S SCIENCE-GOSSIP. 



sod 



Fig. 160. Peronospora ahinearum. Oogonia and Antheridia 

 enlarged 400 diameters. 



is, that the potato 

 is not the plant on 

 which the fungus 

 luxuriates to the 

 greatest extent, and 

 that if we only knew 

 the plant it most 

 affects (probably 

 some South Ameri- 

 can species of Sola- 

 num) we should 

 then find plenty of 

 resting spores easily 

 enough ; [for it must 

 not be forgotten 

 that the potato fun- 

 gus is by no means 

 confined to the 

 potato. It grown 

 on various species of 

 Solanum besides 

 Solatium tuberosum ; 

 it is even not un- 

 frequent on the 

 woody nightshade of 

 our hedges, and it 

 grows upon the to- 

 mato and other sola- 

 naceous plants, to- 

 gether with at least 

 one plant which be- 

 longs to quite a 

 different natural 

 order. On these 

 latter, however, it 

 makes less headway 

 thanupon the potato. 

 As an instance in 

 point, the allied pest 

 of the garden lettuce 

 may be mentioned— 

 Peronospora gangli- 

 formis — first des- 

 cribed by Mr. Berke- 

 ley. Here, if the 

 resting spores of the 

 parasite are wanted, 

 they must not be 

 sought for in the 

 lettuce itself, where 

 they are only spar- 

 ingly produced, but 

 in a plant belonging 

 to the same natural 

 order also commonly 

 afflicted with the same parasite, viz. the common 

 groundsel : tbe resting spores are said to be even 

 more common in sow-thistles than lettuces. 

 Therefore, although it is probable we shall have 



Fi" 



101. 



The Artotrogus of Montagne and Berkeley. 

 Enlarged 400 diameters. 



Fig. 162. Peronospora umbellj- 

 ferarum. Oogonia and 

 Antheridia, enlarged 400 

 diameters. 



Fig. 163. Peronospora infestans. Oogonia and Antheridia from badly diseased leaves of 

 Potato, after a week's maceration in water ; enlarged 400 diameters. 



•0004 inch. Oogonium 



•001 inch. Coat of Cellulose y§ 5 = -00142 inch. 



yet to look to some other member of the natural 

 order Solanaceee to find the resting spores in any 

 abundance, yet, as the resting spores of the lettuce 

 mould can by searching be found in the lettuce 



