THE STUDY OF MINUTE FUNGI. 325 
If the perithecia are associated in little clusters of from two to 
twenty, imbedded in the bark or wood, with long necks which con- 
verge to form a bundle or dise which pierces the bark, it is a Valsa. 
If the perithecia are buried in a brown or black carbonaceous 
mass or stroma, which grows like a cushion on the bark, the necks 
of the perithecia being short and not converging, it belongs to 
the genus Hypoxylon. If this stroma is more developed, grow- 
ing up like a miniature club from one to four inches high, black or 
brown, corky or brittle, with the perithecia immersed in it at the 
upper part, it forms the genus Xylaria. If this club or stalk be 
fleshy, white or red it is a Cordyceps. This genus for the most 
part grows up from dead caterpillars or insects, giving rise to the 
newspaper stories of the vegetable bug. 
Let us now return to our Valsa. Having determined that it is 
a Valsa, we next wish to know its specific name. And, just at 
this point is where the great difficulty in the study of mycology 
commences, where the student is most apt to be discouraged and 
demoralized, and where a little assistance is most needed. To 
determine the species of a Valsa we must first ascertain whether 
the perithecia are in a special stroma, and next whether this 
stroma has a distinct limiting wall or conceptaculum. 
If there is a black, ventricose conceptaculum, pyriform or co- 
noidal in shape, the apex being upwards, with the perithecia scat- 
tered through the stroma, and their long converging necks bursting 
through the conceptaculum, and then through the bark, it belongs 
to the subdivision Circumscripte. Slicing across one of the pus- 
tules of our Valsa, and examining the cut surface we see a black 
ring ; the cut edge of the conceptaculum, within which is a spongy 
mass, the stroma, in which are the perithecia. Of the Valse 
circumscripte, about forty species have been described by my- 
ecologists. To decide which of these species you have before you, 
you next examine the spores. About a dozen species have spores 
like those described above, namely, colorless curved rods. Your 
next step, then, is to ascertain accurately the length of the spores 
before you. And by “ accurately” I mean that you should deter- 
mine their length to within the ;5459 of an inch. The easiest way 
to do this, is by means of an eye-piece micrometer, but if you 
have not this you must rule a scale on a card by aid of your stage 
micrometer and camera lucida. 
On a line across one end of the card, mark off the length of 
