232 Schwartz — The Plasmodiophoraceae and their 
In the roots of Poa annua the root-hairs are frequently swollen at their 
apices to form club-shaped chambers, in which the amoebae or spores of 
L . Graminis may be seen. The nuclei, however, of these amoebae are 
smaller than those in the cortical cells of the root. Figs. 9 and 10 show 
these hairs. It is to be noted that many of the Ligitiera are parasitic on 
the roots of marsh- and water-plants, and further search will probably 
result in the addition of more new species. I have also observed that these 
parasites are frequently associated in the roots with typical mycorhiza. 
This I find to be the case in the roots of Poa annua , Beilis perennis , 
Chrysanthemum Leucanthemum , Mentha Pulegium , and, at times, J uncus 
articulatus. The mycorhizal cells have their nuclei enlarged and degenerate, 
and, as viewed under the microscope, do not give a healthy appearance. 
The three new species of Ligniera are described below. 
Ligniera Bellidis Schwartz, sp. nov. Amoebis raris in cellulis hospitis ; 
sporis 5-6 jax 4-5 /x in acervulos diversiformes conjunctis. Hab. in 
radicibus Compositarum. Sevenoaks. 
This species, which is found in the roots of daisies, is closely related to 
L . Graminis and L. Junci , but appears to be distinct, since grass and rush- 
roots in the immediate vicinity of diseased daisies were found free from 
infection. The habitat from which the diseased plants were obtained was 
a moist one on Fawke Common, Sevenoaks ; the soil, however, was very 
poor and stony. The daisies were plentiful but the plants were very small ; 
about 40 per cent, of them were infected. Microscopic examination of the 
diseased roots showed that the cortical cells were for the most part filled 
with spore-clusters of various shapes, of which the ellipsoid was the most 
common. Very rarely were any amoebae to be seen even in the youngest 
roots. The same parasite has been found by me on the roots of Chrysan- 
themum Leucanthemum , but the roots of other Composites growing in the 
diseased area were found to be unaffected. The disease could be imparted 
from the Chrysanthemum to Beilis , and vice versa. The structure of the 
diseased roots in both plants was similar, and the reserve plant-food in the 
root-cells was inulin. 
Infection probably takes place at the growing root apices, but even in 
these regions of diseased roots only masses of spores are usually to be found. 
This is in striking contrast to the case of M. Triglochinis , in which amoebae 
only are to be seen. The vegetative amoeboid stage of L. Bellidis is shown 
in Fig. 7, and the akaryote stage in Fig. 8. This species, on account of the 
lack of amoeboid forms, is not suitable for the observation of nuclear 
divisions ; the modes of division are probably similar to those met with in 
other genera. 
Ligniera Menthae Schwartz, sp. nov. Amoebis in cellulis radicis hospitis ; 
sporarum soris globosis aut acervulos diversiformes efformantibus ; sporis 
3-5 x 4-5 fx. Hab. in radicibus plantae ‘ Mentha Pulegium * dictae. 
