Homothallism and monosporous mycelia in Coprinus, 209 
VI. COPRINUS NIVEUS. 
From the spores of a wild fruit-body five monosporous mycelia 
were obtained by plating, and they were transferred to dung- 
tubes in the usual way. Of these five mycelia, two yielded 
normal fruit-bodies which expanded and shed spores, two 
yielded rudimentary fruit-bodies which never expanded or shed 
spores, while one did not produce any rudiments at all. It 
therefore seems that, in Coprinus niveus, some monosporous 
mycelia fruit very much more readily than others and that some 
of the mycelia may not be able to fruit at all. It was found that 
compound mycelia of polysporous origin, the spores having been 
derived from a wild fruit-body, fruited much more vigorously 
and several days sooner than any of the monosporous mycelia. 
Thus Coprinus niveus, in contrast with C. sterquilinus, is very 
uncertain in respect to the fruiting of its monosporous mycelia. 
Fruit-bodies of Coprinus niveus were obtained in mono- 
sporous cultures for two successive generations. This result, 
using the symbols already employed, may be expressed as follows: 
F)—> (S+>MM ~F)—> (S>MM +F). 
In Coprinus niveus, just as in C. lagopus and C. stercorarius, 
clamp-connections were found in the following kinds of mycelia: 
(x) several mycelia of monosporous origin, the spores having 
been derived from a wild fruit-body, (2) two mycelia of mono- 
sporous origin derived from two spores produced by a fruit-body 
of monosporous origin, and (3) a compound mycelium of poly- 
sporous origin derived from many spores produced by a _fruit- 
body of monosporous origin (Plate VI, Fig. 11). Hence we may 
conclude, just as we did for C. lagopus and C. stercorarius, that 
Coprinus niveus is homothallic and not heterothallic. 
Since Coprinus niveus is homothallic, it is remarkable that its 
monosporous mycelia are so very uneven in their power of pro- 
ducing fruit-bodies. It seemed possible that two monosporous 
mycelia, if allowed to combine in the same culture vessel, might 
fruit more vigorously from the compound mycelium thus pro- 
duced than either would fruit if kept isolated by itself. Accord- 
ingly sub-cultures were made from three of the five first-made 
monosporous cultures. Let us call these cultures A, B and C. 
A had produced normal fruit-bodies, B only fruit-body rudi- 
ments, and C no rudiments at all. From these cultures six 
dung-tube sub-cultures were made as follows: 
(1) A by itself, (4) A+B, 
Bhi Bein oy, (ShedG: 
(3) (G0 -;, (6) B+C, 
and all the cultures were kept under the same external con- 
ditions. 
