MYi <>II>AOK\I . 



Where this occurs, black patches are frequently formed >.> that 

 the leaves become spotted, but the injury to the host-plant i- by 

 no means so severe as in the following species. 



Ceph. parasiticus Kar-ten. This species i- CMIUIIII.II <>n the 

 leaves of ('"/"///<" and /'////</'// //.s at Buiten/.oi _. It spreads 

 through the whole leaf-tissue blackening and killing' it. Tin- 

 epidermis is blistered and its cells tilled with the ali:a : ultimately 

 the cuticle is ruptured and the stalked sporangia are j.n.- 

 duccd. The swarm-spores germinate in the .-tomatal cavity. 

 or in the adjacent intercellular spaces. 



Ceph. minimus Karsten is parasitic on leaves of '/> '://// 

 Jujiiltii ;it I'luitenzorjj. It permeates the leaf-parenchyma and 

 kills it, the cells after death becoming completely occupied 

 by the a lira. 



Phyllosiphonaceae. 



Phyllosiphon arisari Kuhn. 1 This is a true parasite 

 oliM-rved only on Arixn rn m mli/ni-i' in Italy and the South of 

 France. It causes death of the leaves and is frequently veiy 

 abundant. 



The thallus consists of unicellular, non-septate, much branched 

 filaments containing chlorophyll, and tilling up the intercellular 

 spaces of the spong] p;irenehyma of the host. The wall of 

 the filaments -jives the reactions for cellulose and consists of an 

 miter and a later-formed inner layer, the latter capable of swelling 

 very much to assist in ejaculating the spore-. Tin- chlorophyll 

 corpuscles at first contain no starch, nly oil, which, however, 

 decreases during spore-formation, while the starch inert-. : 

 Tin- spores (aplanospores) are formed in-ide the al^al threads, 

 and ;ire ejected with lire; it force from the extremities of filaments 

 which He under stoinata, and therefoie in the position win-re least 

 ic>i>t;iiice is oll'.-rcd to the swelling inner wall. Chlorophyll i- 

 not jtn-.-ciit in the yoim^ filaments, but it appeur^ in the older 

 p;iil-. >-|HM i;dly about the time of spore-formation, and seem- 

 to be slon-d in the spores. The spores have ;i nucleus and 

 chlorophyll disc. Tln-\- -i-nninalc to a filament which -low- 

 bet \\cen two epidermal cells into ihe intercellular spaces of the 



leaf. 



1 Kiilm, " Kim- in-ill- pan iii^'ln- Al v fr. </. na 



H.ill- , I^Ts : .lii.ii. /li.fiui. Ztituny, lsvj ; x. | lim t 



