50 CASPKR 0. MILLER. 



After remaining on the glass above tlie water for from two 

 to twelve days, the protoplasm collects at one or a number of 

 points at the periphery of the network, and forms sporangia, 

 leaving behind a so-called hypothallus, retaining the shape and 

 outlines of the original network, but much paler in appear- 

 ance. The sporangia vary in number according to the size 

 and vigour of the plasmodia. In one culture there were only 

 two sporangia ; in other cultures the sporangia form groups, 

 the larger of which may contain from seventy to eighty spo- 

 rangia. In the first stage of the formation of the sporangia 

 the protoplasm is of a more yellow colour than that of the net- 

 work. As the sporangia assume their completed shape the 

 colour becomes a brownish red, which changes to a greyish 

 white when the development is completed. 



The sporangia are sessile, resting on a broad base. When 

 isolated they are round, oval, or kidney-shaped. At times they 

 are united, forming a long drawn-out sporangium with con- 

 strictions at irregular intervals. The small oval or round 

 sporangia may measure as little as 0"5 mm. in diameter, the 

 long drawn-out ones may measure as much as 7 mm. On 

 examination with the low power by reflected light the surface 

 shows irregularly shaped small white elevations, between which 

 are darker areas. Under the high power these white areas 

 are seen to consist of aggregations of coarse granules, which 

 dissolve on the addition of hydrochloric acid with the forma- 

 tion of gas bubbles. The sporangia have no columella, and 

 the sporangium wall is colourless. The capillitium is made up 

 of a network of thin, colourless fibres attached to the wall of 

 the sporangium. At the point of communication of the fibres 

 there is a more or less flattened triangular or polygonal thick- 

 ening, containing granules of lime. The spores are smooth 

 and of a brownish-violet colour, measuring 8'5 — 13*5 jn in 

 diameter. The majority of the spores are spherical, but occa- 

 sionally there are oval or irregular forms. From a study of 

 the structure and the arrangement of the sporangia of this 

 Plasmodium, it would appear that it is identical with Phy- 

 sarum cinereum, Pers. 



