28 THE JOURNAL OF BOTANY 
will have so largely increased as to have the semblance of a truly 
eRNeRNG production. In the same way Mimulus Langsdorfit bes 
ed, as, for instance, on both sides of the small stream that 
Fapotinns Carding Mill Valley, Church Stretton, where it is by far 
the most conspicuous and plentiful plant.—J. Cosmo Me.vint. 
NOTICES OF BOOKS. 
Kuesaun, H. Die igh reer e Rostpilze. Berlin: Gebr. 
Borntriger, 1904, Pp. xxxvii, 447. Price 2 ; 
In 1865 De Bary te a paper bearing on the heterccious 
nature of certain rusts. He had proved, by infection experiments, 
that the spores of an Atcidiwm—till then regarded as an autonomous 
genus—would, when sown on another host, produce uredospores 
and teleutospores, the rust form that did so much damage to cereals. 
The idea that such an interchange of hosts existed was not a new one, 
but what had hitherto been a matter of opinion among unscientific 
observers became a matter of fact and a basis for further research. 
Many workers, since his day, have been busy, in various parts 
of the world, tracing the rust from one host to another, always 
settling the question beyond dispute by infection ee are so 
that now the number o a Uredinea, of which the 
— a chronological list of liens discoveries, but remarks that, 
n yet, we are but at the beginning of our knowledge of the life- 
helena of these fungi. 
The subject matter of Klebaln’s books falls into two divisions. 
The first part occupying about 200 pages, deals with the history 
and theory of heterccious rusts. He finds six different types of 
development occurring within the order according to the season at 
which the different forms of spores make their appearance on the 
then discu 
of Aicidiospores and. Uredospores and the conditions most favour- 
able to their germination, with an account of those rusts that have 
succeeded in growing without going through the whole life cycle. 
The question as to the propagation of rust on cereals naturally 
occupies a good deal of attention, the rusts of these grasses being 
of such great economic importance. The persistence of the disease 
may be largely due to the universal cultivation of cereals, few o 
Which -are wholly “ unrusted,’’ and to the action of the wind, which 
has been found to carry heavier bodies than rust spores hundreds 
of miles. He examined microscopically the cotton wool that closed 
the opening of a glass case ghich infection cultures were being 
Carried on, and found many fungus spores, a large percentage of 
which were the Uredospores of cereals. Considering the wide- 
Spread scattering of these spores, Kriksson’s mycoplasma hypo- 
thesis appears to him an altogether unlikely and unnecessary 
explanation of ie spread of the disease. No outbreak of rust 
need ever be looked on as mysterious or unaccountable. In some 
