''^jTiSlal.rS^g!''] PROaRESS OF MICROSCOPICAL SCIENCE. 129 
observations of Tulasne and De Bary by observing tbat spores of 
Varicellaria when placed in a humid atmosphere throw out numerous 
slender circumradiant filaments. In addition to this he has seen other 
filaments arise from the " adjacent disrupted apothecium," and these 
constitute a sort of Penicillium which soon becomes destroyed and 
disappears. He has noticed that the spores when denuded of the 
filaments of Penicillium, displayed in the interior of each cell a white 
corpuscle which "towards the septum separating the cells, in most 
spores stretched out the sporal wall on one side. Thence I sometimes 
saw a white oblong corpuscle spontaneously expelled from either cell. 
When free these corpuscles became larger and especially longer than 
when enclosed within the spore, somewhat deformed and unequal, or 
almost cerebriform on the surface but covered by no cellular mem- 
brane." This the author thinks is the beginning of the thallus of the 
lichen. 
American Observations on Nohert's Test-plate, and How to Count the 
Lines. — Those interested in the resolution of Nobert's lines will find 
two very interesting papers on the subject in the last number of 
'Silliman's American Journal of Science' (No. 138, Second Series). 
The first paper is by Mr. W. S. Sullivant, and comments on Mr. 
Stodder's paper on the "American Naturalist" for April last. The 
footnote to this paper deserves notice. The author, speaking of 
Dr. Woodward's photographs, says, " The first fifteen bands are 
sharply and clearly resolved into the t7-ue lines ; the fifteenth band, 
however (which is ruled to the 90,000th of an English inch) requiring 
a hand-glass magnifying four or five diameters to show its lines dis- 
tinctly." Mr. Sullivant makes a suggestion, too, which we should take 
into consideration — it is that an eager observer may be pushed by his 
imagination to see almost anything that he desires to perceive. The 
second paper, by Dr. and Col. Wood ward, contains matter already brought 
under the notice of the Eoyal Microscopical Society. The following 
directions for counting the lines in the highest bands that can be 
resolved may be useful : — ^"If a cobweb micrometer is used, the micro- 
meter eye-piece should be firmly clamped in a stand screwed to the 
table, so that the eye-piece is close to the end of the microscope-tube, 
but does not touch it — a piece of black velvet being used to coinplete 
the connection. The motion of the micrometer-screw now commu- 
nicates no tremor to the microscope, and all difficulty in counting 
the lines seen (whether real or spurious) disappears." Still better 
than this is the following method : — The microscope being set up in a 
dark room, as though to take a photograph, and the eye-piece being 
removed, the image of the band to be counted is received on a piece 
of plate-glass in the plate-holder, and viewed with a focussing-glass, 
on the field-lens of which a black point is marked ; as the focussing- 
glass is moved on the plate from side to side, the black point is moved 
from line to line. The lines may thus be counted with as much ease 
and precision as though they were large enough to be touched with the 
finger. 
