490 Brier ley.—■The ‘ Endoconidia ’ of Thielavia basicola , Zopf. 
Zopf but overlooked by nearly all later observers, is always closed by 
a middle layer of cell-wall substance. 1 Rarely a pitted transverse wall, 
apparently affording protoplasmic continuity, could be distinguished in the 
vegetative hyphae. 
Discussion. 
The development of ‘ endoconidia * is a process distributed sparingly 
but widely in the Fungi; and examples have been repeatedly described. 
In consequence the extensive literature on the subject is very scattered, and 
the synonymy of the forms has become greatly confused. Such species 
belonging to more than thirty genera are known, but it is probable that 
these may all be legitimately included in the following genera 2 — Helotium , 
Sordaria , P Male a, Thielavia , Pyxidiophor a , Sphaeronema , Thielaviopsis , 
Sporoschisma , Chalara , Cytosporella , Alternaria , Endoconidium , Hymenella , 
Bloxamia. 
A critical consideration and analysis of the published figures and 
descriptions, and in many cases of the Fungi themselves, showed an 
extraordinary similarity of form and, structure, size, and, where known, 
developmental details. 
This likeness is so fundamental and complete as to nullify the dis¬ 
crepant accounts of the several authors, and. considering the extremely 
stereotyped character of the few methods of spore production known in 
Fungi, almost to preclude the doubt that possibly more than one process of 
development may be responsible. 
1 According to Zopf the chlamydospores are exogenous and their walls laid down simultaneously 
in the hypha (Simultane Scheidewandbildung, loc. cit., 1890) : whilst Duggar states (loc. cit., 
p. 212) that their ‘early stages of formation differ only in size from the endospores’; that is, they 
are endogenous and formed by basipetal septation. (Compare Thielaviopsis paradoxa , Sphaeronema 
adiposum. ) My observations show that the spores are formed successively as thin-walled, barrel¬ 
shaped cells during the development of a hypha of strictly limited growth. They remain in this 
condition for some time and then gradually and simultaneously thicken their walls. It is after the 
walls have attained their mature thickness that the brown to black colouring matter is deposited. 
A slight ‘ lagging ’ in this latter process is apparent in those cells towards the apex of the chain. 
Frequently one to three or four cells at the base and rarely one or two at the apex remain thin- 
walled and colourless. Gilbert (loc. cit.) terms these the sterile segments; but I have frequently 
found them capable of immediate germination like the ‘ endoconidia ’. This is interesting because 
the thick-walled chlamydospores will only germinate after a period of rest, in my experiments not less 
than ten weeks. This period may be very considerably shortened and even eliminated by subjecting 
the spores to a freezing process, to the action of dilute mineral acids, or of gastric juice. It is to be 
noted that in the case of gastric juice it is the acid and not the pepsine which renders premature 
development possible, the latter of itself having no effect on germination. 
2 See Additional Literature. Those Fungi which may be referred to the genera Psiloniella , 
Glycophila, Sporendonema, Malbranchea , and Conioscypha are not included in this list. In these 
cases what has been described as ‘ endoconidial formation ’ is better termed ‘ aplanospore forma¬ 
tion ’, for each cell of the filament gives rise by rejuvenescence to a spore. Liberation occurs by the 
rupture of the mother-cells or the breaking down of the entire filament. The confusion has arisen 
by the frequent occurrence of this mode of spore formation in hyphae of limited growth, such that an 
appearance simulating an ‘endoconidial cell’ with a chain of spores is produced, 
