99 
The spores of this Uredo chrysanthemi placed in water germinated 
in a few hours with great vigour. In the course of 24 hours SO 
energetic was the growth of their germ-tubes that they intertwined 
with one another so that the mass of spores, floating on the culture 
drop looked for all the world as if it had become mouldy, but the 
apparent hyphae were only germtubes. If the spores, which are 
globose, be allowed to become dry and are examined microscopically 
in that state it will be seen that one segment of the sphere is very 
much stronger than the rest, so that the spores collapse laterally 
in such a way as to resemble those indigo-balls sold by grocers under 
the name of “thumb blue” and used for laundry purposes. Each 
spore looks as if it had been compressed on one side between the 
finger and thumb. 
With regard to the Ustilaginee the same differentiation of species 
on biological grounds has been demonstrated, only in these cases 
corresponding morphological characters usually co-exist. [he work 
of Jensen, Brefeld, Swingle, Kellerman, Magnus, Dietel, Cocconi, 
Kuhn, &c., is recognised by all. The old species Ustilago segetum 
is now known to comprise 
Ustilago tritici (Pers.) on wheat. 
»,  hordei (Pers.) on barley. 
» nuda (Jens.) on barley. 
9  perennans (Rost) on Avena elatior. 
which differ not only in spore measurements, &c., but in the manner 
in which the spores germinate as well as in naked eye characters. 
For instance, the two barley species, one is firm compact and solid, 
while the other consists of an evanescent dusty mass. Jensen has 
further pointed out the existence of two species of Ustilago on the 
cultivated oat which although they have not yet been recognised as 
British probably occur with us. ‘They are distinguishable by their 
naked eye characters inasmuch as one U. avene Pers. destroys the 
whole head as U. nuda on barley does: while the other U. /evis K. 
and §. does not destroy the outer palee. Besides this, the spores of 
One species are smooth but of the other rough. 
Two well marked species of Ti/letia have long been recognised on 
wheat, one with areolate, the other with smooth spores. Only the 
former has been observed in Great Britain but the existence of the 
other should be borne in mind, | 
itn ne Ustilago which some botanists call Schreeteria 
hee Sera of the fruit of Veronica hederacea, in which 
ae ae S ee a striking feature, has been added to our flora as 
ee Pie val se Tulasne which Mr. Greenwood Pim detected 
ot ae eae of Scilla bifola in April 1895. ‘The last addition 
tie he; : ungi is the curious Urocystis filipendule which Mr. 
ae ed on the foliage of Spiraea filipendula last year. 
periment [ have performed this year may interest you. 
