1 78 Bailey*— Puccinia malvacearum and the Mycoplasm Theory. 
with the production of promycelia and sporidia ; sometimes ‘ oidial * 
germination may be found to occur in the same pustule, and occasionally 
all the germination in any one pustule will be of the oidial type. On the 
other hand, he says, spores taken from pustules which had broken out on 
plants which had passed the winter out of doors and had lost their leaves ' 
in the normal way, germinate almost always with ‘ oidia 
These conclusions are supported by a long table containing the results 
of 34 experiments, but the evidence is not very convincing owing to the 
frequent occurrence of both sorts of germination from one pustule and to 
the fact that in certain cases one pustule has given entirely sporidial 
germination, whilst another from the same plant has given entirely oidial 
germination. 
The present writer has conducted a fairly extensive series of germina- 
tion experiments, the details of which will be found in the Appendix to this 
paper. 
The deduction made from these experiments is that the ‘ oidial 5 type 
of germination is merely the result of abnormal conditions and can be 
produced at will by varying the environment. 
If the teleutospores are completely submerged in water, germination 
will be almost exclusively of the ‘ oidial ’ type, whilst the same spores, 
exposed to moist air, will produce promycelia and sporidia in the normal 
way. 
The experiments are divided into„six series. In the first three series, 
spores, teased apart or united in pustules, were placed either on or under 
the surface of water in watch-glasses. It may be assumed in this case that 
all those spores which remained at the bottom of the water were thoroughly 
wetted, whilst those which floated on the surface were either partially or 
wholly wet or, less frequently, quite dry. 
An examination of the results of these three series shows that spores 
which remained at the bottom of the water germinated exclusively in the 
‘oidial’ manner, whilst those at the surface germinated in either one way or 
the other. In almost all cases the spores on the surface showed a mixed 
germination, and in a few cases the two cells of the one spore germinated 
differently. One such case is illustrated in Fig. 1. 
Eriksson, in his description of the oidial type of germination, .calls 
attention to the swelling at the proximal end of the germ tube. In our own 
cultures this swelling has frequently been noticed, but is by no means an 
invariable feature of this type. 
In Series IV and V complete leaves were detached from diseased 
plants and supported in such a way that one half of each leaf was submerged 
in water whilst the other half was exposed to the air. 
The air around the leaves was kept thoroughly moist by covering the 
whole with a large bell-jar. Series VI was carried out similarly w r ith 
