230 Schwartz— The Plasmodiophoraceae and their 
some forms resembling the akaryote stage in the cells of young tumours, in 
which the disease was in an early stage and the infection recent. Should 
these forms prove to be the akaryote stage, this stage would seem to be 
displaced and would appear earlier than is the case in the other genera. 
T. parasitica causes tumours on Ruppia rostellata ; it has also been 
stated to have been found on Zannichellia palustris by Hisinger in 1887. 
Maire and Tison, however, have recently found it plentifully in R. rostellata , 
growing in close proximity to Z . palustris , which was uninfected. This 
throws doubt on the statement that the latter is a host-plant. I have found 
multinucleate amoebae in the root-hairs of plants of Z. palustris which were 
otherwise free from infection ; these amoebae might be a species of Ligniera , 
or, on the other hand, they might be T. parasitica . 
The genus Molliardia, M. and T. 
In M. Triglochinis , M. and T., which is the sole representative of this 
genus, neither the akaryote stage nor spore clusters have been observed as 
yet. This species was formerly known as Tetramyxa Triglochinis , but has 
been removed from that genus, since the latter is characterized by the 
presence of tetrads of spores. It is the cause of swellings on the stems and 
inflorescences of Triglochin maritimum and T. palustre ; these swellings are 
similar in structure and development to those of the Veronica. It has been 
described by Maire and Tison ( 14 ), who state that the mitoses in the schizont 
stage are similar to those of the other genera, with the exception that 
abnormal mitoses are not uncommon, and the presence of uninucleate 
amoebae in the plant-cells is frequent. It is not unlikely that a spore stage 
will be found, in which case M . Triglochinis will possibly be transferred to 
one of the other genera. 
The genus Sorodiscus, Lager and Winge. 
6*. Callitrichis , Lager and Winge, is the cause of tumours on the stems 
of Callitriche autumnalis^ and is the only species of this genus. It has been 
described by Winge ( 26 ), who states that it is very closely related to 
Sorosphaera Veronicae , from which it differs in having the spores arranged 
in flattened hollow spheres or ellipsoids. Winge has observed in 5 . Calli- 
trichis the typical vegetative mitoses which, he states, occur simultaneously 
in all the nuclei of an amoeba ; this statement applies also to the other 
genera. He states further that the axes of the dividing nuclei (i. e. their 
elongated karyosomes) are generally parallel ; this is certainly not the case 
in the other genera I have examined. Winge also observed the two 
mitoses which occur just before spore formation, the number of chromo- 
somes showing a reduction from sixteen to eight. 
