108 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Chromophyton Rosanoffii.*— N. Wille found, associated with 

 Conferva, Ortliosira, Spirogyra, and Mougeotia, a brown palmella-like 

 organism which he identified with Woronin's Chromojpliyton Bosanaffii.^ 

 As described by the discoverer, he found two kinds of zoospores, one 

 smaller and rounder, the other larger and ovoid, each with a single 

 cilium. After swimming about, they attach themselves by the 

 anterior ciliated end to a filamentous alga, and become encysted ; the 

 encysted form contains a red eye-spot, and again developes zoospores. 



The organism which proceeds from the ovoid zoospores is identi- 

 fied by Wille with Ehrenberg's flagellate Epipyxis utriculus, and the 

 one which proceeds from the spherical zoospores with Stein's flagel- 

 late Chrysopyxis bipes. He concludes therefore that Chromophyton 

 Bosanoffii is not an independent organism, but that it must be regarded 

 as a palmella-form of two flagellate Infusoria. 



Phyllosiphon Arisari.+ — F. Schmitz has undertaken a fresh ex- 

 amination of this organism, parasitic in Italy on the leaves of 

 Arisarum vulgare ; his results differing in some respects from those 

 already obtained by L. Just.§ 



The thallus of the parasite spreads extensively through the inter- 

 cellular spaces of the parenchyma immediately beneath the palisade- 

 parenchyma of the leaf; and in these spaces the filaments branch 

 normally and almost invariably dichotomously, lateral branches being 

 very rarely seen. Their average diameter is from 25 to 35 /x ; when 

 the apical growth has ceased they increase in diameter to about 60 /x, 

 and the formation of spores commences. The filament dichotomises 

 repeatedly, and thus becomes changed into a more or less ramifying 

 tuft of branches of equal or unequal length, which are sometimes 

 swollen into a club-shape at the extremity. The spores then begin 

 to be formed in the interior. This portion is, however, never 

 separated from the rest of the thallus by a septum. The vegetative 

 and the spore-forming stage of the thallus are not sharply separated 

 the one from the other. The wall of the filament is simple at the 

 growing extremity, double in the older parts, the outer layer being 

 cuticularized. The growing apices of the filaments contain a parietal 

 layer of protoplasm, with strings of the same substance crossing the 

 central cavity, and containing drops of oil. The protoplasm contains 

 a number of nuclei of irregularly spherical or lenticular form, each 

 of which has usually a nucleolus; the nuclei increase rapidly by 

 division. 



In the growing apices the protoj^lasm is completely colourless, 

 but further backwards it gradually assumes a yellowish green and 

 ultimately green colour. This is not due to a general colouring of 

 the entire protoplasm, but to a number of excessively minute disk- 

 shaped chlorophyll bodies dispersed through it. It contains also a 

 number of globular starch-grains, which vary greatly in size, and 



* SB. Bot. Ver. Prov. Brandenburg, 1882, pp. 49-50. 

 t See tills Jourual. i. (1881) p. 100. 



X Bot. Ztg., xl. (1882) pp. 523-30, 539-55, 5G3-73, 579-83. 

 I See thia Joumul, ii. (1882) p. 3U1. 



