XYt.OMYi KTi:s. 11. "> 



lint by conjugation or union of two cells of tin- mycelium 

 .separated oft' from tin- ends of two hyphae by transver-e walls. 

 A.S a result of conjugation, a zygospore i- produced, which is 

 a restiug-spore and corresponds to the oospore of the < )omycete.-. 

 The zygospore puts forth a germ-tube, which becomes a mycelium 

 bearing sporangia on sporangiophores. From each sporangium, 

 spores, never swarm-spores, are set free, germinate, and produce 

 a mycelium. Sporangia similar in form to the zygospores may 

 be asexually produced on the mycelium. The unicellular and 

 much-branched mycelium grows into its substratum, and i- 

 nourished as a rule saprophytically. The Entomophihoreat cause 

 important insect-diseases on Muscidae, Cabbage r>uttertlie-. and 

 caterpillars of Trm-ln-n ^i/ii^ui-i/n (the Pine Beauty). 



Another common group of the /yjoinycetes, the Min-m-im. 

 penetrate into bruised places in living fruits, and produce decay 

 (see p. ISO). Some other Zygomycetes are parasitic on fun-i 



nididbolus), some on animals. 



(3) OO.MVCKTKS. 



These fungi possess a one-celled and much-branched mycelium. 

 In their vegetative structure they most nearly resemble algae 

 like I'ltu,-],, ,-in. Reproduction is brought about, asexually by 

 mean.- of swarm-spores formed in spurangia (eonidia also occur): 



y by oospores derived t'roin oo^onia and antlieridia. 

 There are three families of Oomycetes : Saprolegniaceae, M 



-ii/iif, and !' r<>iii>*]K>r<iif. Two of tho.- groups ' "iitain 

 ]>ar;i>itie forms: ,SW//, ,,/,_,/,//,/,-, ,/, (,.//. J-7///A/ prolifera, dangerous 

 to Fish and Crustacean-): ami Peronosporeae. 



PERONOSPOREAE. 



The -T.-ater number of the Peronosporeae live as para-ite> in 

 the ti-siies of higlie.- jilaiits, and obtain nourishment generally b\ 

 means (1 f haiistoria. The mycelium, in earlier life at least, has no 

 dividing sepia, and -em-rally grows in the intercellular spaces of 

 the ho-t-plaiit. and sends hau-toria into the cells. lleproduct ion 

 is rlfeeird asexually by lormatioii of swarm-.spoi'es in -poran 

 nnl >e\ually by means of oospores. The latter arc produced 

 iVom the fertilization of an ovum in an oci'jMiiiiiin by an ant hei idium 



\\ho-c eouieiits ; hrou-li a fert ili/atioii-tube penetrating the 



