-3i— 
(Reprinted from the Journal of Botany, September, 1905,) 
NEMATODE GALLS ON MOSSES. 
By H. N. Dixon, M^A., F.L.S. 
When recently examining specimens of Porotrichurn alopecurum Mitt., 
gathered in 1894 at Becky Fall, Lustleigh, South Devon, I was struck by 
what appeared to be terminal male flowers on the tips of the secondary 
branches and branchlets, forming hard, yellow, tumid, bud-like bodies, on 
some plants very numerous and conspicuous ; in one case I counted as many 
as fifty on a single stem. The apical position, as well as the fact that the 
stems were fruiting ones (the species being dioicous) of course precluded the 
idea that they were male flowers, and on dissection they proved to be bodies 
of a gall-like nature, containing numerous minute Nematode worms, or 
Anguillulce. 
Galls of this nature appear to be very uncommon on mosses — I have 
only once come across them elsewhere among the many thousands of speci- 
mens that have passed through my hands in the last twenty years or more: 
they have recently been described in two papers in Hedwigia, for the refer- 
ences to which I am indebted to Mr. A. Gepp. Monkemeyer published a 
short article ( Hedwigia , xli. Beiblatt 22, 1902) on “ Hypnum fluitans L. mit 
Anguillulagallen ; ” and again, within the last few weeks, a more detailed 
article has appeared by Schiffner {Hedwigia, xliv. 218, 1905), “ Beobachtun- 
gen fiber Nematoden-Gallen bei Laubmoosen.” The former writer describes 
similar galls on H. fluitans , and refers to their occurrence on other Harpidia, 
as noted by Warnstorf, especially on H. aduncum Hedw. Schiffner adds 
considerably to the number of species of moss acting as host-plant to the 
galls, having found them on several species of Dicranum , and, what is curi- 
ous. most of these occurred' in quite dry stations, instead of in the aquatic or 
moist situations which are the usual habitat for these Anguillulidce. He 
also detected them on H. cupressiforme , where they occurred at the apex of 
the branches ; and he points out that this effectually disposes of the supposi- 
tion that the galls might originate from male flowers, modified by the infec- 
tion of the Anguillula. This conclusion is entirely confirmed by the case of 
the Porotrichurn now recorded, where the galls all occur at the apex of the 
ultimate branchlets, where flowers are never produced. 
In all probability the Nematode is the same in all these galls, as Schiff- 
ner found them to be the same on the various species of Dicranum , etc., 
from which he obtained them ; and Monkemeyer’s figures of those in the galls 
of H. fluitans exactly recall those which I obtained from Porotrichurn alope- 
curum. Moreover, his description of the alteration in structure produced in 
the leaves composing the gall in H. fluitans agrees exactly with my own 
observations. 
I have on only one other occasion Observed anything in the nature of a 
gall on a moss, viz. on a specimen of Eurhynchium Swartzii Hobk., gath- 
ered in a ditch in Yardley Chase, Northamptonshire, in 1887. The nature of 
the gall remained at the time undetermined, and the moss was put on one 
side; but recent examination in the light of the facts described above shows 
the contents of the galls to be similar, and Eurhynchium t must be added to 
the list of those genera already known to be infested by the Anguillulce. 
