326 
W. B. Mercer, 
On the Morphology and Development of 
Phoma Richardiae n. sp. 
By 
W. B. Mercer, B. Sc. 
(Vans Dunlop Scholar, University of Edinburgh.) 
(Schluß.) 
Considerable difficulties lie in the way of direct proof of the theory 
above stated, in particular the power the fungus has of growing through 
ordinary porous membranes. By growing the fungus on an agar drop 
separated from another agar drop by a thin sheet of collodium, it was 
hoped that any substances formed in the one inoculated would find their 
way through the collodium into the second. But the fungus grew through 
the collodium and 
produced fruit on the 
agar on either side*). 
It grew through 
parchment paper, 
and goldbeaters’ skin 
under similar condi¬ 
tions. 
It is unfortuna¬ 
tely impossible to 
utilize the agar of 
old cultures for ger¬ 
mination experi¬ 
ments. By the time 
it becomes dark co¬ 
loured it is usually 
half dried-up, and 
in any case it is im¬ 
possible to find fresh 
spores brought on to 
it, among the thou¬ 
sands of old. 
Old cultures 
were, however, boiled 
up with water and 
filtered. Small num¬ 
bers of spores were 
then brought into hanging drops of the filtrate; they germinated normally. 
Evidently if a poisonous substance is formed, it is either not removed, 
or it is destroyed by boiling water. 
1) MlYOSHI (Jahrb. f. Wiss. Bot. 1895 , 28, p. 269 ) found that Pénicillium glaucum 
and Botrytis cinerea both bored through layers of collodium 1,5 mm thick, the hyphae 
of the latter swelling and growing in a spiral form in the membrane. In the present 
case the hyphae were straight and slightly attenuated as they passed through the 
collodium. 
Fig. 6. i — 4 : Young plants from extruded spores on Ca¬ 
sein gelatine. — 5— 7: Young plants on gelatine + l°/o 
Oxalic acid. — 8 — 10: Young plants on plum agar at 
34° C. (Fig. i —5 and 7— 10 = 353 / t ; Fig. 6 = 263 / 1 .) 
