Relationship to the Mycetozoa and the Chytrideae. 233 
This species I found at Chislehurst, in the roots of some plants of 
Mentha Pulegium which were growing in profusion on the border of a pond 
on the Common. Other marsh-plants growing with the Mentha , such as 
A tisma ranunculoides , Beilis perennis , and various species of J uncus, were 
examined, but were found to be free from the Ligniera. 
Microscopical examination of the older roots showed the infection to 
be confined to the outer cortex, the cells of which were largely filled with 
spore-clusters. These clusters were mostly ellipsoidal in shape ; spherical 
ones were also common, and sometimes a tetrad or a single or double row 
of spores were to be seen. The individual spore is similar to that of other 
species. In the young branch-roots amoebae were sometimes to be seen, 
although the L. Menthae displayed the same tendency to early spore 
formation as I observed in L. Bellidis , but not in so marked a degree. The 
vegetative nuclei are typical ones ; they are, however, somewhat smaller 
than those of L. Graminis . I have not observed the typical e cruciform’ 
method of division of these nuclei, although the usual method of division is 
probably of that form. I have, however, observed in one of the amoebae 
some abnormal vegetative nuclear divisions in which the division was 
effected by an ordinary karyokinesis, as is shown in Fig. 6. This confirms 
the observation of Maire and Tison, who found a case of typical karyokinetic 
division in the schizont stage of Molliardia. The akaryote stage shown in 
Fig. 2 is comparatively common. I have not observed any karyogamy 
prior to spore formation, but the form is not well suited for cytological 
study owing to the difficulty of finding diseased material. 
The amoebae are small and irregular in shape, and several of them may 
be seen in a plant-cell, so that schizogony is not uncommon. The infected 
cells occupied by the organism in its amoeboid form occur in small groups 
and are rarely isolated. The amoebae are shown in Fig. 1. I have only 
found this disease in the one locality mentioned above, but, on the other 
hand, I have not had the opportunity of examining plants from more than 
two other localities, so I am unable to speak as to the rarity or otherwise 
of its occurrence. 
Ligniera Alismatis, Schwartz, sp. nov. Amoebis raris in cellulis hospitis ; 
sporarum soris, iis Spongosporae similibus, aut sporis in ordinibus aut 
globose dispositis ; sporis 3 ju, x 4 (jl. Hab. in radicibus plantae ‘ Alisma 
Plantago ’ dictae. 
This species I found parasitic in the roots of Alisma Plantago growing 
in some trenches near Dunton Green, Kent. It resembles L. Bellidis in 
that the amoeboid form is very rarely seen. The spore-clusters are not 
exactly similar to those of other species of Ligniera , since in the latter the 
clusters usually exhibit an axial symmetry, while in L. Alismatis the 
boundaries of the spore-clusters are not, as a rule, so definite as in the other 
