486 Brier ley.—The ‘ Endo conidi a ’ of Thielavia basicola , Zopf. 
bridge between two vacuoles is now cut off from the conidiophore by 
a septum which grows inwards in the form of a ring or diaphragm, finally 
closing in the centre (PL XXIII, Figs. 3-4). The conidium almost in¬ 
variably contains two vacuoles, thus presenting a very characteristic appear¬ 
ance (PI. XXIII, Fig. 5 a). The oil-globules within the vacuoles may 
remain discrete, appearing as a cluster of grapes ; or fuse to fill the entire 
vacuole so that it reacts as one large oil-globule ; or be present as a fine 
emulsion within the vacuole. Rarely oil-globules may be found lying 
freely in the cytoplasm (PI. XXIII, Fig. 4). 
Liberation of the Conidia. 
The liberation of the first conidium is brought about by a tangential 
splitting of its walls, which are thus differentiated into an outer closed sheath 
and an internal cell (PI. XXIII, Figs. 5, 5 <2, and 6). An exhaustive micro¬ 
chemical analysis of the conidiophore prior to this occurrence was carried 
out, but no layer corresponding to a middle lamella could be detected in the 
transverse wall, nor any incipient line of splitting in the lateral walls. 
Almost simultaneously with its differentiation, the sheath is ruptured 
at or near its apex, and the enclosed conidium projected about one-quarter 
to one-third of its length beyond the open mouth of the sheath, appearing 
like a cork in a phial (PI. XXIII, Fig. 7). Rarely the rounded tip of the 
sheath is torn away and may be observed fitting as a tiny cap on the end of 
the protruding conidium (PI. XXIII, Fig. 7 a ). 
The protoplasm in the conidiophore is thus not naked at its apical 
surface, but bounded and separated from the sheath by a very hyaline and 
delicate transverse wall (PI. XXIII, Fig. 7) whose thickness is one-half that 
of the normal cell membrane. This wall, which has been overlooked in all 
previous work, now becomes convex to the spore, and, owing to the growth 
of the conidiophore up through the sheath, pushes out the first conidium. 
Meanwhile the nucleus in the conidiophore again divides, one daughter- 
nucleus passing to the apical region (PI. XXIII, Figs. 5, 8, 9), which is then 
cut off as the second conidium, by a transverse wall formed in the manner 
already described. This wall is always immediately below the original 
position of the first wall, and when it is differentiated into two layers, 
the line of splitting being in the same tangential plane and meeting that 
between the conidium and the sheath, liberates the spore. 
The latter is pushed out in the rear of the first by the development of 
the subsequent conidia, which are formed in like manner (PI. XXIII, Figs. 5, 
8 , 9 ). 
The conidia thus possess cell membranes which are only one-half 
the thickness of a normal cell-wall, this also being true of the sheath and 
• elongating apical region of the conidiophore (PI. XXIII, Fig. 7). Except 
