136 Mr Biffen, Note on some factors in the 



Note on some factors in the spore-formation of Acrospeira 

 mirabilis (Berk, and Br.). By R. H. Biffen, B.A., Emmanuel 

 College. 



[Read 4 March 1901.] 



Acrospeira mirabilis is a fungus found as a parasite on Spanish 

 chestnuts 1 and so far nothing beyond the mode of development of 

 its characteristic chlamydospores, traced by Berkeley in 1861, has 

 been published. 



This note on some of the factors concerned in its spore- 

 formation is but a portion of the results obtained while making 

 the attempt to trace its life history and so to find its true place in 

 the present system of classification. 



The spores found by Berkeley and Broome were developed 

 from the subterminal cell of a row of three or four, coiled into a 

 spiral of from one and a half to two turns. These cells all became 

 fused together so that the spore was partially invested. When 

 ripe it was brown, thick-walled, and covered with rounded warts. 

 The investing cells were similar, but thinner-walled and poor in 

 protoplasmic contents. 



From its thick walls one might conclude that this spore-form 

 was a resting-spore like the chlamydospores (or paulospores of 

 Klebs) of Hypomyces spp. but it seems to be the spore-form which 

 serves for the rapid reproduction of the fungus. 



In spite of the fact that Acrospeira is a parasite it may be 

 grown readily as a saprophyte on various media. On germination 

 the large cell only puts out a hypha, the further development of 

 which was determined chiefly by the food supply available. 



Thus if sown on an extract of peas and ten per cent, gelatine 

 the mycelium grew slowly and remained sterile altogether, though 

 transferred repeatedly to fresh supplies of pea extract. If however 

 it was transferred to pieces of sterilized chestnuts it gave rise, in 

 the course of four or five days, to numbers of the invested 

 chlamydospores, similar to those described by Berkeley. 



On sowing on slices of sterilized melon chlamydospores were 

 again formed but a large percentage of them were abnormal and 

 resembled the teleutospores of Puccinia or of Phragmidium in 

 shape, owing to the development of two or of three of the cells to 

 form spores without the preliminary coiling. 



1 Berkeley and Broome, Anns, and Mag. Nat. Hist., 1861, p. 449. 



