The Lifc-liistory of Mycetozoa. By G. Lister. 363 



sporangia ; sporangium- walls are secreted, and the remainder 

 of the protoplasm, after the capillitium has been formed, divides 

 into spores ; before spore-formation the nuclei undergo a reduc- 

 tion division, and eacli daughter-nucleus forms the centre of a 

 spore. 



We may now turn to the course of events in Ccratiomyxu (PI. X 

 and PI. XI, fig. 7). The sporophores are fragile wldte bi'anching 

 or anastomosing structures, often appearing in great abundance on 

 the surface of much-decayed wood. The general aspect of a large 

 development closely resembles that of a thin effused Polypoms. 

 The colourless ellipsoid spores are borne on slender stalks bristling 

 over the surface of the sporophores ; they are readily detached, 

 and are dispersed by currents of air or washed away by rain, which 

 completely dissolves the gelatinous sporophores from which they 

 have fallen. Notwithstanding the naked and unprotected condi- 

 tion of the young spores as compared with those of the Endosporese, 

 Ceratiomyxa must be regarded as a sviccessful species, for it is 

 abundant in both tropical and temperate regions where decaying 

 wood occurs. The ripe spores differ from those of the Endosporese 

 in possessing four nuclei. On being moistened the spore-wall is 

 thrown off with a jerk from the swelling of the contents ; the 

 latter at first show slight amoeboid movements, and often put out 

 pointed pseudopodia, but very soon the four nuclei divide by 

 mitosis, and the whole cell separates successively into two, four and 

 eight parts ; each of the eight uninueleate divisions acquires a 

 flagellum and swims off as a minute swarm-cell (PL XI, fig. 7, a-h). 

 The further history of these swarm-cells or flagellulpe has not been 

 traced ; they have been observed to withdraw their flagella and 

 become amcebulte, but these have not been observed to conjugate 

 in pairs or to form plasmodia ; from analogy with the Eudosporese 

 however it is probable that such processes occur. Dr. Jahn was 

 able to count eight chromosomes in the nuclei of the swarm-cells 

 and sixteen in those of the plasmodium, showing that when the 

 latter stage is reached the haploid nuclei have become diploid. As 

 the Plasmodium lives within rotting wood it is invisible till it 

 comes to the surface to fructify. It then emerges in the form of 

 transparent cushions of jelly. If such a cushion be placed on a 

 glass slide and kept moist, the jelly is seen to be traversed by a 

 dense network of protoplasmic veins in which rhythmic streaming 

 of granules can be watched. The streaming was clearly observed 

 when the shock of placing the specimen on glass had caused part 

 of the Plasmodium to gush out from the main cushion ; the injured 

 part recovered in half an hour and spread in a thin fan, in which 

 a tine system of interlacing currents was seen ; later the fan 

 developed into a flat sporophore adhering to the glass, and formed 

 healthy spores. Five successive stages in the development of the 

 sporophore were distinguished by the Eussian botanists, Woronin 



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