Domestic Notices. 75 



there had been produced a greyish slimy substance, of a very offensive 

 smell. 



"The black mass divided in a drop of distilled water, exhibited under 

 the microscope a number of long and oval, very irregular shaped dark 

 bodies, interspersed among the cells of the potato. Many of these cells 

 appeared lacerated, but this might partly have been produced by the me- 

 chanical action of dividing, although I think not altogether. The greyish 

 slimy mass was semi-transparent and indistinct, even mixed with the dis- 

 tilled water and exposed to the strongest light I could throw. 



"In order to discover a remedy for this disease, I decided on applying 

 various substances to this fungus, with a view of effecting its decomposi- 

 tion, and examining their action under the microscope. The first application 

 was salt, and the action of this was so instantaneous and decided, that I did 

 not proceed to any other. 



' ' A portion of the dark substance was placed on a piece of glass on the 

 microscope stand, in a drop of distilled water, and then thoroughly exam- 

 ined : a little salt on the fine point of a penknife was then added ; a nearly 

 instantaneous change took place ; the dark colored masses separated, much 

 of them seemed to pass away, and instead appeared numerous dark slate 

 colored globular bodies, which I easily recognized as the spores or reprodu- 

 cing bodies of the fungus. With the grey slimy substance, the effect was 

 still more striking : all the indistinct slime disappeared, the mass became 

 clear and transparent, and left nothing but these innumerable dark globules 

 floating about in the drop of water. 



" It seemed to me then that the salt destroyed all the vegetation of the 

 fungus, leaving nothing but the reproducing spores, which are probably 

 indestructible by salt. The spores of fungi are the bodies by which they 

 are reproduced and spread, and are analogous to the seeds of other vegeta- 

 bles, and these spores are generated in such enormous quantities, that many 

 fungi, like this on the potato, spread with inconceivable rapidity ; but in 

 order to vegetate, they require certain favorable conditions and circum- 

 stances which yet require much investigation. These favorable conditions 

 are, in my opinion, prevented by salt, as it destroys the fungus vegetation. 

 Therefore, wherever the disease existed this year, I recommend a liberal 

 supply of salt to be spread on the soil, and trust it will eradicate the evil : 

 it is, at all events, a remedy which cannot do much injury if it does not 

 succeed. 



During the examination of the black substance, I of course recognized 

 the grains of starch, which appeared sound ; but wishing to know whether 

 the fungus had affected them, I added a little iodine : the grains immedi- 

 ately took the usual purple color, and I think were not at all injured : in- 

 deed, it appears to me that the injury takes place by the rupturing of the 

 cellular parts of the potato. 



I am aware that it requires some practice to judge well of the appear- 

 ances under the microscope, but I repeated these examinations six or seven 

 times, and always with the same results ; still I should be very glad to have 

 them repeated by others, whether their correctness be confirmed or not." 



