On the Morphology and Development of Phoma Richardiae n. sp. 
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may be again divided in a longitudinal or oblique direction. They contain 
oil drops. During growth their colour changes from yellow-brown to 
brown-black; with age they may be impenetrable by light. The amount 
of constriction at the cross walls is very variable, but is usually well marked. 
These conidia are not produced in great abundance, especially on some 
media. On liorse-dung agar, and on plum agar kept at 12 ° C — in both 
of which cases aerial mycelium is well developed — they are the most 
abundant. They never precede pycnidia formation; the majority are deve¬ 
loped late in the life of the culture. Since they are thick-walled and 
dark-coloured, and arise on aerial mycelium, it is impossible to see 
their structure while still growing. By cutting out pieces of agar 
from PETRi-dish cultures and mounting in Lactophenol 1 ), a sufficient 
number of examples in different stages of growth were obtained to enable their 
manner of evolution to be traced (Fig. 3 , 41 — 43). The conidia consist 
of special branches of the mycelium marked out in their earliest stages 
from vegetative branches, by their darker colour, and by the frequency 
of cross walls (Fig. 3 , 41). The base of the branch for a varying length 
remains unaltered, to form a conidiophore. Towards the apex the cells 
swell up and thicken their walls, to form the first conidium (Fig. 3 , 42 , 
43). The apex meanwhile continues growth as a yellowish tube divided 
by cross walls into short cells (Fig. 3 , 43, 44). A basal portion under¬ 
goes little alteration, forming the “Zwischenstück“, while cells towards 
the apex again swell up and thicken there walls to form the second 
conidium (Fig. 3 , 43). The same process may be repeated several times. 
The first conidium may continue growth during the formation of the 
second; in some cases it remains smaller than the second (lowest chain 
Fig- 3 , 34). 
Any cell of the conidium may give rise to a lateral branch developing 
in the same manner as the parent. In this way the chains may come to 
be branched (Fig. 3 , 33, 36 ). 
7. Mycelial gemmae. 
Various gemma-like bodies are formed in old agar cultures. Since 
no two are exactly alike it is difficult to classify these growths; roughly, 
they may be divided into three groups, viz: — 
a) The first variety consists of modified branches of the mycelium 
(Fig. 4 , i —5). The evolution of this type of gemma, which follows 
closely that of the brown conidia, was followed by marking the position 
of a few in the earliest stages in a moist-chamber culture, and making 
drawings at intervals of a few days (Fig. 4 , ia and e). Short branches 
arise and become divided by cross walls at close intervals (Fig. 4 , ia)\ 
the cells thicken their walls and swell very irregularly, those in the 
middle as a rule becoming larger than the rest (Fig. 4 , ib and c). The 
apex may continue growing, the cells thickening their walls as formed 
(Fig. 4 , id and e). From one or more of the cells short tubes may 
proceed, which divide and swell in the same manner as the parent. 
Simple growths may resemble distorted brown conidia (Fig. 4 , 2, 4) while 
1) Lactophenol consists of approximately equal parts of Lactic acid, Phenol, 
Glycerine and Water. 
