TYPHULA TRIFOLII was obtained from Poland
in the form of sclerotia which had been found in
samples of Clover seed. Both generic and specific
criteria have been found insufficient in identifying
this,and allied fungi. pp. 45-46.
Using the sclerotia as inocula, the fungus
has been grown in pure culture. Haploid aad
diploid mycelia are only distinguishable by cytological
characters, macroscopically the mycelia are
alike. The haploid mycelium has plain septa and
usually one nucleus in each cell, the diploid
mycelium has clamp connections at most septa and
usually one pair of conjugate nuclei in each cell.
Anastomosis and movement of nuclei between the two
cells thus connected occurs in both haploid and
diploid mycelia even where there is no question of
heterothallism. pp. 12-26.
Monospore cultures usually produce neither
sclerotia or fructifications but in some these
structures are formed which are therefore made up of
haploid h.yphae. Haploid sclerotia are smaller than
diploids but otherwise very similar. Haploid
fructifications are also smaller than diploids but while haploids are always fertile in artificial
culture, diploids are sterile. Spores borne on
haploid fructifications are smaller than those on
diploid fructifications. pp 38-49.
Clamp connections are usually formed
according to Bensaude's first method but it is
believed that some are formed according to her
second method. pp 26-35.
Typhula Trifolii is heterothallic; certain
compatible haploid strains have been grow} together
to form diploid mycelia. p.59. The cytology of
anastomoses between compatible mycelia has been
studied by means of a modification of the agar film
technique as used by Sass. p.8.
When anstomosis occurs between two compatible
haploid mycelia migration of nuclei occurs, followed
by the upsetting of the equilibrium of the cells of
invaded hyphae. LIigrating nuclei appear to be in
an abnormal physical state since they may be seen
unstained in living hyphae. p. 72-78. Some indig-
enous nuclei in invaded cells disintegrate.
Nuclei migrate by means ofnthe partial or
complete dissolution of septa. In the former case
"half walls" are formed, sometimes the side wall at
such a partially dissolved septum is bulged out
apparently to increase the aperture through which
the nucleus passes. Alen the invading nuclei have reached the younger parts of the hyphae, which may
be quite close to the point of anastomosis or
several cells distant, they conjugate with indigenous
nuclei and the first clamp connections appear.
nnastomosis between diploid and haploid hyphae has
much the same result in causing migration of
nuclei from the former to the latter so that it
also becomes diploid.
Thus the work of Lehfeldt on Typhula
erythropus has been confirmed. A discussion is
given on the significance of this confirmation
with regard to recent work on the method of
diploidisation in Coprinus.