•ifli; 



EXPEBIMl-jyTS WITff PLA.XTS 



Tln' Spores of the Mould are (like the spores of the 

 bacteria) resistant cells which are not injured by 

 exposure to dry air and are, in fact, carried about by 

 the wind so as to s<'atter the Mould everywhere. When 

 ripe the spore-case bursts, so as to set the spores 

 fi'ee. 



In addition to these spores (called asexual spores) 

 there often occur lrii\c:er ones (called sexual spores, 



or zygospores, because 

 they result from the union 

 of two branches), which 

 are formed, as shown in 

 Fig. 2'20, by two branches 

 coming together and fu- 

 sing so as to form a large, 

 thick -walled spore of a 

 deep black color. These 

 spores are larger, more 

 resistant, contain moi-e 

 nutriment and give rise 

 on germination to a more vigorous growth than the 

 ordinary asexual spores. 



Another very connnon Mould is the Oreen Mould 

 (I'enicillium) of che<_^se, bread, jellies, etc. In this 

 ^lould the spores are in long chains at the end of the 

 stalk (Fig. ^^1), and are not enclosed in a spore-case, 

 as in the Black Mould. 



What effect do these Moulds have on the substances 



220. Formation of zygospores of the Blaok 

 .Mould of loi-inl: iit the left two branches 

 touching. ti> tlie riglit stages in the fu- 

 sion, tlie ht.st lieing the fully formed zygo- 

 spore. 



