3 H 
Review : 
growth such as is never found elsewhere in their free state. In 
fact, Brefeld suggests that in certain cases the development of a 
fungus may he carried a step further by artificial cultivation than 
can ever take place under natural conditions. An apparent instance 
of this is the production of the ascocarps of Penicillium glaucum, 
the special conditions for obtaining which by growing this mould on 
slices of bread are fully described. By taking the necessary steps, 
Brefeld never failed to obtain the ascocarps when he required them, 
but, so far as is known, they have never been met with in nature, in 
spite of the ubiquity of the fungus itself. 
The sawdust of various woods furnishes another valuable 
culture medium when damped with a nutrient solution, largely on 
account of its porous nature, and is particularly suitable for those 
forms which grow principally upon wood. The usefulness of certain 
ripe fruits for the cultivation of Fungi is often overlooked. Bananas 
may be specially mentioned: after removal of the peel, the flesh 
which is not too rich in sugar and sufficiently porous in structure 
is obtained in a sterile condition and after leaving it for a short 
time to become soft, it forms a most favourable culture medium, 
especially for the Mucorineac. 
Brefeld, from his wide experience does not speak so favourably 
of the various nutrient media prepared with the addition of gelatine 
or agar-agar, which are so generally employed for cultivating Fungi. 
He admits that they have their special advantages, particularly in 
the cultivation of bacteria, also for obtaining pure cultures from a 
mixture of fungus-spores, for transporting living cultures of Fungi 
for long distances, for the biological analysis of air and water, etc., 
but Fungi grown on them never reach the same luxuriant growth 
as they do on other substances, more particularly on bread and 
sawdust. 
We may now turn to the external conditions which can in 
certain cases exercise an influence, favourable or otherwise, on 
artificial cultures of Fungi and hence must be taken into consider¬ 
ation. In this connection, the well-known work of Klebs has 
already shown to how great an extent the phenomena of reproduction 
in the lower Fungi and Algae may be influenced by external 
circumstances. Some further instances of this are contained in 
the present volume. 
When Fungi are grown in nutrient liquids the degree of 
concentration is of importance. Thus, in very concentrated 
solutions, Sporodinia grandis produces zygospores only, while in 
dilute solutions the asexual sporangia alone are formed. It is 
found that many parasitic Fungi will grow only in very dilute 
nutrient solutions. When solid media are employed the amount of 
moisture they contain plays an important role. Coprinus stercorarius 
forms exclusively sclerotia when grown on a decidedly damp 
substratum, but on a drier substratum the cap-shaped fructifications 
are produced without the previous formation of sclerotia. 
Nor can the influence of light be neglected ; it has not been 
shown to be essential for the vegetative development of any fungus 
but without a sufficient intensity of light, a number of forms are 
unable to produce their fructifications. Coprinus stercorarius and 
C. plicatilis show the phenomena of etiolation in the stipe, which 
grows to an exorbitant length when the fungus is grown in the dark 
