CHAPTER V. COMPARATIVE REVIEW. CHYTRIDJEAE. l6l 



though close affinities. With this reservation we will first proceed to describe the 

 points of form which are common to them all. See the Figs. 75-77 below. 



The sporangia are cells of varying shape and diameter in the different species, 

 and are often furnished with one or more wart-like or neck-like processes, which 

 finally discharge the spores from their swollen and projecting apex, or which, as in 

 Chytridium Olla, are cast off like a lid for the same purpose. They are furnished 

 when fully grown with a moderately thick wall of cellulose, and densely filled with a 

 uniformly finely-granular fatty protoplasm, which at length divides simultaneously into 

 numerous spores. In most species the division is preceded by separation of the pro- 

 toplasm-granules, which are colourless or coloured yellow, orange, or rose, according 

 to the species, into as many groups divided by narrow hyaline streaks, in each of which 

 the granules then coalesce to form bodies of successively larger size, and ultimately a 

 single sphere consisting chiefly of fatty matter. This sphere of fatty matter then lies, 

 usually excentrically, in the body of the swarm-cell, which otherwise consists of 

 hyaline protoplasm and allows a nucleus to be seen in the larger forms 1 . Such a 

 swarm-cell when set at liberty is roundish or elongated in shape, and is furnished 

 with one cilium which is several times longer than the diameter of the body. The 

 sphere of fatty matter is much more frequently, but not always, brought near the point 

 of insertion of the cilium ; exceptions to this structure occur in most of the species 

 only as monstrosities. But in some there is no fatty sphere (Chytridium macrosporum, 

 Ch. roseum, &c.). The spores of Olpidiopsis Saprolegniae, Woronina, and Rozella 

 have according to A. Fischer always two cilia. 



The spores are discharged from the sporangia by the process of swelling 

 described in section XX, and in some species are at first held together in a mass 

 by mucilage, from which they are afterwards gradually set free one after another ; 

 in other species they leave the cavity of the sporangium one by one. Where the 

 dimensions and the speed of their movements allow of exact observation, the cilium 

 is usually seen to follow the body in the process of release from the sporangium. The 

 movement in the water is described as being clearly in many species a hopping 

 movement; a progression by hops in no strictly determinate direction alternates 

 in longer or shorter periods with a state of quiescence and each hop is associated 

 with a stroke of the cilium like the stroke of a whip. But this kind of movement is 

 not found in all the species. The spores of Nowakowski's Chytridium Mastigotrichis 

 and the highly phototactic spores of Polyphagus Euglenae and of Strasburger's 

 Chytridium vorax move forward with moderate speed and uniform rotation round 

 their longitudinal axis and with the extremity that has no cilium in front, while the 

 cilium follows passively behind. The time that the movement continues varies in 

 each case, being seldom more than an hour, often much less ; in a few cases, as 

 in Synchytrium Taraxaci, it is considerably more. Towards the end of the period 

 of movement an undulating change in the outline of the body often takes the 

 place of the phenomena which have been described, together with an amoeboid 

 creeping on a firm substratum, in which the cilium is dragged behind. 



The resting-cells or resting-spores of the Chytridieae are on an average nearly or 

 quite as large as the sporangia, and are distinguished from them by thick, often 



1 See above, pp. 107-109. 

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