PH.^ZOSPORE.^ 257 



prolonged into a slender colourless beak ; in one of the angles is a 

 brown chromatophore ; and attached to the centre of the opposite side 

 a single short cilium, and near it two pulsating vacuoles, but no pig- 

 ment-spot The zoospores appear to germinate directly without con- 

 jugation. Lagerheim has also detected, on different individuals from 

 the zoospores, peculiar resting-spores, through the vitality of which 

 Hydrurus remains dormant through the summer and autumn, its active 

 life extending only through the cold season. Hydrurus is placed by 

 Rabenhorst and Cooke among the Palmellaceae. 



Chromophyton AVor. is an epiphytic organism which vegetates and 

 hibernates within the hyaline cells of the leaves of Sphagnum and other 

 aquatic mosses. In this state it consists of unciliated naked masses of 

 protoplasm with pulsating vacuoles, and endowed with an amoeboid 

 motion. While still within the cells of the host, these bodies become 

 invested with a delicate cell-wall, multiply by repeated bipartition, and 

 assume the condition of resting-spores, the endochrome being now of a 

 brownish red colour. From these resting-spores are developed zoospores, 

 minute ellipsoidal or nearly spherical bodies, 8-9 p.. long and 4-6 /j.. 

 broad, with a single cilium, a contractile vacuole, and a bright yellow 

 or yellowish brown pigment-disc, consisting of a substance apparently 

 identical with the diatomin of the Diatomacece. These zoospores are 

 imbedded in a colourless mucilaginous matrix, in which condition they 

 float in large numbers on the surface of the water of bogs in the form of 

 a fine yellow dust. When completely immersed in water, the zoospores 

 are set free from their investing mucilage, and at once begin to swarm. 

 After a time each zoospore develops a second colourless gelatinous 

 envelope, with a tubular opening below, through which it absorbs water. 

 In this encysted condition, having now lost its cilium, it multiplies by 

 bipartition. Although two forms of zoospore have been obser\-ed, one 

 much smaller than the other, no process of conjugation has been detected. 

 Cornu describes a second species of Chromophyton with stalked bodies 

 which may be sporanges, and a siliceous coat like that of diatoms. 

 Although in some respects presenting a resemblance to a degraded 

 form of Ph^osporeae, it is possible that Chromophyton may be a stage 

 in the development of some organism belonging to a totally different 

 class. In some respects it may be compared to the Chytridiaceae 

 among Fungi. 



Literature. 



Woronin— (Chromophyton) Bot. Zeit. , 1S80, pp. 625, 641. 



Rostafinski— Hydrurus u. seine Verwandtschaft, Krakow, 1882 (Ann. Sc. Nat., xiv. , 

 1882, p. 5). 



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