CH. I] Introduction to Fungi 7 
into a small drop of water on a coverslip large enough 
to cover the top of the chamber; smear the top with 
vaseline and place on it the inverted coverslip. The 
spores are now in a hanging drop in a moist chamber 
and can be watched under the microscope. After 
about 12 to 24 hours the oval spores send out small 
projections which continue to grow; later on cross 
walls are formed (see Fig. 3). 
In water growth ceases as soon as the food in the 
spore is used up. If, however, a food solution is used 
for a hanging drop instead of the water, the tube 
continues to grow, branches and gives rise to the 
Fig. 5. A Ward’s tube. A, paraffin wax; B, vaseline; C, the 
hanging drop. 
same kind of mycelium as that on which the spore 
was borne. 
A method now in common use for the study of 
fungi consists in making cultures of them in such 
substances as plant extracts, meat extracts, gelatin, 
or agar-agar (prepared from sea-weed) or a mixture of 
some of these. The medium is freed from living 
organisms by means of heat and then infected with 
fungus spores or pieces of mycelium. Saprophytes and 
many parasites grow and form spores; some parasites, 
however, such as rusts, will not grow in this way. The 
experiment is usually carried out in tubes stopped with 
cotton wool or in Petri dishes (see Fig. 6). 
