476 
POPULAR SCIENCE REVIEW. 
which, as far as we at present know, differ materially in their 
reproduction from the other dust-like or uredinous fungi with 
which they have long been associated. Dr. de Bary proposes 
the union of these with the mould-like fungi of the genus 
Peronospora (to which the mould infesting the potato belongs), 
so as to constitute by themselves a group apart from the 
genera with which both have heretofore been associated. 
Whether his views will be accepted by mycologists time will 
speedily prove. Under any circumstances microscopical and 
botanical science will reap considerable benefit from his 
researches. 
WHITE MILDEWS OR BLIGHTS. 
Notwithstanding the inconvenience to ourselves of calling 
very different fungi by the same common name of u mildew,” 
the popular mind does not recognize the inconvenience, since 
it scarcely troubles itself to inquire whether they are not all 
the same thing. In obedience to this custom we again write 
of “ mildew,” or “ blight,” as it is called in some districts, but 
of a very different kind to that which is so detrimental to 
growing crops of corn. In the present instance it is our 
intention to illustrate a group of fungi which are exceedingly 
common, and which: differ greatly in appearance and structure 
from any to which we have had occasion to allude. To obtain 
a general knowledge of these forms let our reader proceed at 
once to a clump of rank grass : if it be his fortune to dwell in 
the country, the walk of a few yards will suffice. Let him 
examine this clump more carefully, perhaps, than he has been 
accustomed to do, and we venture to predict that he will find 
some of the leaves covered with what appears to be a dirty 
white mould, or mildew. One of these leaves should be col- 
lected as carefully and conveyed to the microscope as speedily 
as possible, taking care not to touch or brush it against any 
other object so as to disturb the arrangement of the delicate 
little threads upon its surface. If a small portion, say about 
an inch, be cut from this leaf with a sharp pair of scissors, and 
laid upon a slide, or pinned down upon a strip of sheet cork so 
as to keep it flat and then submitted to examination under the 
microscope, with an inch power, a beautiful forest of crystal- 
line vegetation will be observed. If the examiner on this 
occasion should not possess a binocular microscope we are 
sorry for him, because in that case he will not see all that is 
to be seen under the greatest advantages. If we ever truly 
enjoy looking through such an instrument it is on an occasion 
like this, when a low po^ver is all that is needed and the object 
is required to be seen in relief. It is scarcely possible to 
convey an adequate idea of the beauty of such a scene as the 
