On two species of Heterospornan particularly Hetero sporium echinulatum 137 
face view of the epidermis was obtained as well as of the inner tissues 
of the leaf. This section showed an infection hypha which had pene¬ 
trated the middle lamella between two adjacent epidermis cells (see 
fig. 47). 
On the 4 th March disease spots were seen due to the infections on 
the 5 th February. The spots were greyish in colour with a dark spot in 
the centre, and extended to both sides of the leaf; their size was from 
1—1.5 mm in diametre. In this case four weeks had elapsed between 
inoculation and the reappearance of the parasite. 
Experiment VIII. 
On March 8 th another Dianthus-^mi was infected in the same 
manner as before, the spores being taken from old disease spots in two 
cases, and from a pure culture in another. Three leaves were inoculated. 
The solution containing the spores also contained pieces of aerial hyphae, 
and aphid casts which helped to mark the places of inoculation. These 
areas were kept moist every day by the addition of a drop of water led 
by means of a paint brush on to the inoculation areas. 
On the 16 th March one of the inoculated leaves was cut off, the 
inoculated area was cut out, and free hand sections were cut. The sec¬ 
tions were killed in lacto-phenol, and stained in Bleu-coton G4B. Many 
sections showed the presence of mycelium in the tissues from the epi¬ 
dermis to the middle portions of the leaf. In one or two cases the 
infecting hyphae had branched into two. In some instances the epidermis 
had been torn away in cutting, so that in these cases the actual manner 
of penetration could not be made out. In one or two sections, however, 
infecting hyphae were observed to pass direct through the epidermis 
(fig. 48). In one case an infection through a stoma was observed (see 
fig. 49). 
The other two leaves were also removed, and their inoculated areas 
cut out and killed in weak Flemming solution. 
Experiment IX. 
On the 25 th March 1912 five leaves of a new Dianthus plant were 
inoculated with spores obtained from two PETRi-dish cultures on salep 
agar. It was ascertained that numerous spores were present. The 
inoculated areas were indicated with ink marks as in a previous ex¬ 
periment and after inoculation a bell-jar was placed over the plant. On the 
same day one old lower leaf, and one young leaf were removed from the 
plant, the cut ends gummed up with glycerine-jelly and taken up to the 
laboratory where they were placed in a PETRi-dish under a couple of glass 
slips such as those used for damp chambers 1 ). These slips helped to 
keep the leaves flattened out. Through the circular opening in the glass 
slips the leaves were inoculated with the same material as above. Previous 
to inoculation the waxy coating of both leaves had been removed by 
gently rubbing the upper epidermis with a rag. 
1) See Klebahn (1), p. 489. 
