Researches on the Life-history of Parasitic Fungi. 
BY 
C. K. BANCROFT, B.A. 
Formerly Major Scholar of Trinity College, Cambridge. 
With Plate XXIV. 
I. Cladosporium herbarum, Link. 
HE genus Cladosporium is a comparatively old one, having been 
X founded by Link in the year 1791. The species Cladospormm herbarum 
was described by the same observer in the following terms:—‘ atrovirens, 
densum, effusum, floccis septatis.’ 
The species is of somewhat wide occurrence; almost everywhere the 
dead remains of plants can be seen to be covered with dark, sometimes 
almost black patches formed of its conidiophores. The conidiophores are 
olive and are arranged in tufts which are frequently large and dense. The 
conidia are olive, continuous at first and becoming later typically once 
septate ; they measure on the average 18-20 x 8-10 /z, and are produced at 
the tip of the conidiophore in short chains which sometimes remain attached 
so that they may become larger and twice or even thrice septate. Clado¬ 
sporium herbarum in its life-history will be shown to be connected with 
another conidial form belonging to the form-genus Hormodendron ; this 
form Hormodendron will be shown to be parasitic on several plants, causing 
disease, and it is proposed first to treat with this disease and after to deal 
with the relations of the conidial form to Cladosporium herbarum . 
The disease caused by the form Hormodendron and the evidence 
of its parasitic nature. 
For some time past the green foliage of many different species of plants 
has been seen to be suffering with a disease which takes the form of large, 
irregular holes in the lamina of the leaf. The damp summer of last year 
seems to have been particularly favourable to the spread of the disease. Of 
the species which have frequently been found to be affected in this way the 
following are given :— 
Brassica oleracea{ Cabbage), Cucumis sativa (Cucumber), Cucumis Melo 
(Melon), Arctium Lappa (Burdock), Catalpa bignonioides , Althaea rosea , 
[Annals of Botany, Vol, XXIV. No. XCIV. April, 1910.] 
