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PKOGEESS OF MICKOSCOPICAL SCIENCE. 
Fusisporium Solani and its Besting Spores, — In reference to this 
fungus, Mr. W. G. Smith sends us the following quotation from an 
article which recently appeared in the ' Gardeners' Chronicle ' from 
his pen : — " Fusisporium Solani is a fungus which very commonly 
occurs on diseased potatoes in company with Peronospora infestans. 
One is as destructive to the potato as the other ; and Mr. Berkeley, 
writing of the former in 1857, describes it as a second enemy of the 
potato, ' equally destructive with the Peronospora, and, according as 
the two are separate or combined, different appearances arise. In 
some cases,' continues Mr. Berkeley, ' it produces an extreme degree 
of hardness, inducing a condition like that of the mummified silk- 
worms. Sometiijies, on the contrary, it causes rapid and loathsome 
decay, especially when in company with the Peronospora.' Like the 
latter, it suddenly appears on the potato plant, carries on its work of 
destruction, and vanishes. Till now I believe the resting condition 
of Fusisporium Solani has never been described. In my attempt to 
work out the life history of Peronospora infestans, the undoubted 
resting spores of the Fusisporium came to light in the following 
manner: — A quantity of badly infected potato leaves were selected 
and isolated last July with the view of watching the Peronospora. 
As the presumed oospores of the latter gradually appeared, there also 
appeared much smaller bodies, which also went to rest ; these were so 
similar in size and appearance to antheridia or dead zoospores, that 
they were thought to belong to one or the other. When I recently 
placed some of the presumed oospores of Peronospora in pure water 
to promote germination, all the smaller bodies at once burst, and 
in the short space of six hours developed into perfect plants of 
Fusisporium Solani. In size the spores measure about the 2317^ 
inch in diameter ; they are palish brown in colour, with a very finely 
muricated outer coat, and a light central nucleus. The Fusisporium 
is frequently produced close to the resting spore, and I have observed 
the direct germination and production of the Fusisporium in in- 
numerable instances. How these resting spores arose last year I am 
not certain, but it is not improbable that they may be a different 
condition of the aerial fruit broken up into four parts." 
Microscopical Structure of BocJcs. — This subject, which was almost 
unknown a few years ago, becomes now more popular every day. 
The latest investigation in this direction is that of M. Michel Levy, 
which is reported in the 'Revue Scientifique,' and abstracted as 
follows by the ' Academy ' (May 20) : — In relation to acid rocks, it 
is observed that under the microscope they present the appearance of 
being composed of elements formed in succession at different epochs. 
The oldest crystalline elements are frequently broken, and worn or 
rounded, at their edges. They bear unmistakable marks of the 
mechanical actions that accompanied their eruption. They may be 
distinguished as ancient crystals, or crystals en debris, from the more 
