MOULDS. ■ 143 



o 



Anotlier mode of germination in t!ie acrospores 

 of tlie potato mould has been observed by tbe same 

 eminent mycologist. This results when the spores 

 are sown upon a humid body^ or on the surface 

 of a drop of water. The acrospore emits from its 

 summit a simple tube_, the extremity of which 

 swells into an oval vesicle ; into this the contents 

 pass, and it isolates itself by a partition from the 

 germ-tube. Thus it becomes a duplicate of the 

 acrospore from whence it was derived. This 

 secondary body has also the power of producing a 

 tertiary cellule in a similar manner. Both the 

 second and third cellule, when immersed in water, 

 produce zoospores in the ordinary manner, as above 

 described. 



Yet another and a third mode of germination 

 is described by the same author, in which the 

 acrospore emits from its apex a germ-tube, which 

 elongates considerably; and into this long and 

 tortuous tube the contents of the acrospore pass, 

 and accumulate at the opposite extremity. 



The germ-tubes, produced in the manner last 

 described, when developed on the surface of a 

 favourable plant, perforate the cells of the epidermis, 

 or enter by the stomata. In the case of the potato 

 mould, the germ- tubes enter by the stomata; but 

 in the majority of species the germ-tubes do not 

 enter by the natural pores of the leaves upon which 

 the acrospores are sown, but perforate the cellules, 

 and thus effect admission into the tissues of the 



