460 



NATURE STUDY AND LIFE 



two in length, on the tips of which the beadlike spore 

 cases are plainly visible to the naked eye. 



We may next have the pupils substitute for the culture 

 medium in their bottles various solid materials bread, 

 potatoes and other vegetables, meats, and a variety of dif- 

 ferent fruits. Each pupil may provide a different mate- 

 rial, and in this way the class will gain a notion of how 

 omnivorous the moulds are. 



An experiment that must not be omitted consists in 

 inoculating a number of different fruits with mould spores, 



FIG. 190. DIFFERENT KINDS OF MOULD 

 a, milk mould; b, blue mould; c, black mould; d, white mould 



to observe the process of decay. Here again the children 

 may take different fruits for variety's sake some apples, 

 some pears, others plums, peaches, grapes, each child 

 taking different varieties so far as practicable. We will 

 suppose that the pupils have each three fruits of the 

 desired variety. Having cautioned them to secure per- 

 fect specimens with stems attached and no breaks of the 

 skin, let them each put one fruit aside, perfect ; let them 



