426 Horne and Williamson .— The Morphology and 
centration of the acid and hydrogen-ion concentration of the medium will 
be lowered. In the case of a species highly tolerant of acid, these factors 
sooner or later exercise a retarding influence on growth: if the species is 
relatively intolerant, growth might be accelerated (E. viridescens is moder¬ 
ately tolerant). 
5. In the sections of this paper relating to growth in acids many cases 
have been specified where fungal growth does not appear to bear any 
definite relation to hydrogen-ion concentration. This behaviour may be 
due in part to differences in molecular concentration. Tannic acid (mole¬ 
cular weight 1785) affects the growth of E. viridescens considerably more 
than gallic acid (188), although the hydrogen-ion concentration of the tannic 
acid media is more favourable to growth than that of the gallic acid. 
Tartaric acid (168) affects both E. viridescens and E. catenulata more than 
malic acid (134). Further support is obtained from the growth data 
determined for E. viridescens in the tannic extract agar series (Fig. 21); here 
the curves for the o-i, 0-25, 0*5, and 1 per cent, concentrations exhibit great 
dissimilarity, the progressive retarding influence on growth being strikingly 
correlated with increased molecular concentration. 
6. In media containing N/50 malic, citric, tartaric, and gallic acids 
respectively, the growth-rate is approximately the same for E. viridescens : 
it is the same for a few days, but differs later, in the case of E. catemdata. 
Variations of this kind in the growth-rate in equimolar concentrations of 
acids may be due, in part, to changes in the media owing to growth activities 
which may vary in character with the acid employed. On the other hand, 
some acids may exercise a specific toxic action, at particular molecular con¬ 
centrations, on a given fungus, in which case a somewhat similar effect would 
be produced. 
IV. Systematic Position and Specific Descriptions. 
The general characteristics of the genus Eidamia as proposed by 
Lindau ( 11 ) are: hyphae branched, septate, white; conidiophore upright, 
branched, septate, narrow at the apex and bearing a circular swollen end 
cell; sterigmata arising radially on the swollen head, pointed; conidia 
in chains, hyaline ; bulbils produced on side branches and branches similar 
to the conidiophores produce single-celled chlamydospores of rounded 
form and yellow-brown colour. 
Up to the present time only one species, possessing all these character¬ 
istics, has been included in the genus, viz. E . acrenionioides. The writers 
consider the inclusion of the two new fungi, E. catemdata and E. viridescens , 
in this genus is justifiable on the grounds of their general resemblance to 
E. acremonioides in possessing colourless branched septate hyphae pro¬ 
ducing two types of spores, namely conidia and single-celled macrospores 
