17 
ON SOME FACTS IN THE LIFE HISTORY OF 
ACROSPEIRA MIRABILIS (BERK. & BR). 
By R. H. Biffen, M.A. 
With Plate II. 
In the Annals and Magazine of Natural History for 1861 
Berkeley and Broome described a curious mould fungus, found 
on Spanish Chestnuts at Bristol, under the name of Acros peira 
mirabilis. The genus so founded* still remains mono- 
typic, and beyond Berkeley’s account of the development of 
the one spore form known to him, nothing further has been 
published with regard to its life history. It is always included 
in the Hyphomycetes in the Family of the Dematieze on account 
of its dark-coloured “ conidia.” 
Berkeley’s detailed account of the fungus is to be found in 
his Introduction to Cryptogamic Botany (p. 305). I quote it in 
full. “ But, perhaps, one of the most curious [Sepedoneit] is a 
species which occurs, not unfrequently, in imported Spanish 
Chestnuts. The white substance of the two large cotyledons is 
completely traversed and altered in texture by the mycelium 
of the mould, while a few fertile threads are produced in the 
free space between the cotyledons. If a slice of the diseased 
cotyledon be placed on damp soil under a bell-glass, in two or 
three days the threads are beautifully developed, and exhibit 
under the microscope a very curious condition. The tips of the 
fertile ramuli are curled into a little spiral, which after a time 
consists of about three articulations. All of these swell, but the 
second the most, so as to appear to be supported at its base by 
the other two. The integument becomes slightly rough and at 
length strongly granulated, like the spore of a Genea, and 
eventually, in some cases, a second spore is added at the tipe” 
Masseet describes the hmngussalso= but: as follows <— 
“Sterile hyphae blackish-olive, floccose, interwoven, fertile, 
erect, vaguely branched above, tips of branches curved and 
closely septate ; conidia subglobose, lateral near the tips of the 
branches, dark-coloured, minutely warted, 15-20 mu diam.” 
*Not to be confused with Acrospira (Mont.) 
+Sepedonei. A subdivision of the Hyphomycetes with the fertile threads 
scarcely distinct from the mycelium, and the spores very abundant. 
f¢ A Text-book of Plant Diseases (Pp. 435). 
