- 8 3 — 
that S. papillosum holds the place of first importance. It is only in very wet 
places and under exceptionally favorable conditions that the other three sphag- 
nums acquire the soft, bushy habit. 
How to prepare sphagnum samples for assay purposes — First of all, in col- 
lecting select a characteristic specimen: one that really is a fair sample of the 
area of moss that it is intended to represent. Try to include only one kind of 
sphagnum in each sample — don’t get a mixture. Pull up a good, generous 
double-handful, pick out any “weeds,” squeeze out the water, and wrap, it up 
in a piece of newspaper. Tag the package with a number, so that you will 
know just where it came from. Collect plenty of samples from different areas, 
and make each one good and big — it will be as light as a feather when dry, parcel 
post rates are low, and large samples are easier to judge than small ones. When 
you get it home, loosen each bunch up with your fingers and spread it out in 
the air to dry. When nearly or quite dry, separate each sample into two lots 
and ship one of these to headquarters for examination, keeping the other (num- 
bered in duplicate) for reference. For mailing, samples can be wrapped in 
newspaper or wrapping paper. 
Send for a sample of surgical moss , if* you are in any doubt as to what to 
look for. Specimens for examination can be sent to George E. Nichols, Botan- 
ical Adviser on Sphagnum, Yale University, New Haven, Conn. 
POROTRICHUM NOT THAMNOBRYUM 
Elizabeth G. Britton 
In the May Bryologist, Professor Chamberlain records the changes pro- 
posed by Dr. Nieuwland 1 2 for the genus Thamnium Br. & Sch. 
The truth of the matter is that there is no need for another generic name, 
as Porotrichum (Brid.) Mitt, is quite sufficient for both groups of species. It 
is a refinement of hair-splitting to attempt to separate so large and characteristic 
a genus, which may be recognized by macroscopic characters, on microscopic 
differences in the markings of the teeth, which do not hold constant! Anyone 
who has studied the key and illustrations given by Brotherus 2 and. then turned 
to the genus Porotrichum and found that the key breaks down in various w'ays, 
will realize that it is a most troublesome and needless separation of a perfectly 
natural group of species, which furthermore are most generally found sterile. 
Braithwaite 3 says: “This large genus of 175 species appears to connect the 
Hypnacece with Neckeracece, having the peristome of the former, but the habit 
and aerolation of the latter The newer name Thamnium cannot be main- 
1 J. A. Nieuwland. Critical Notes on New and Old Genera of Plants — X. Am. Midi. Nat. 
3:50-51.1917- 
2 Teeth of the outer peristome striate. 51. Thamnium. 
Teeth of the outer peristome papillose or striate only below. 47. Porotrichum. 
Engler & Prantl. Pfl. fam. fasc. 226, p. 852, 859. 1906, figs. 629-633. 
3 British Moss-flora 3 : 197. 1963. 
