142 J. SAUNDEKS NOTES ON THE MYCETOZOA. 



century, and when seen projecting from the ruptured capsules 

 it certainly has a strong resemblance to a tiny tuft of woolly fibre. 

 The Trichias may often be observed in compact groups of an inch 

 or two in diameter on rotten tree-stumps, or scattered over the 

 foliage of mosses and liverworts which grow in these situations. 

 This does not imply that the Mycetozoa have fed on the living 

 tissues, but that they have been nourished on the underlying 

 decayed vegetation, and have crept out to the surface when 

 ready to form their spores, so that these may be distributed by 

 the wind. 



There is yet another genus {Arcyria) which is by no means rare, 

 in which both spores and capillitium vary in colour, and are either 

 a pale yellow, or range from a delicate flesh tint to a deep crimson. 



The presence of this woolly substance is always helpful in field- 

 work in determining whether a specimen under observation is a 

 Mycetozoon or not. But if an observer be in doubt, it is always 

 advisable to secure an unknown form for careful examination at 

 home, as otherwise a rare species may be cast aside as worthless. 

 It should be borne in mind, however, that about one-fifth of the 

 known British genera have no capillitium. But even these in 

 some cases ( Crihraria) have a delicate framework which lines the 

 wall of the sporangium and gives it support. At first this external 

 skeleton may be mistaken for a true capillitium, and hence may 

 deceive the novice as to the true position in classification of the 

 species under consideration. Close and extended observation will, 

 however, soon enable the observer to distinguish between these 

 two organs. 



The contents of the sporangia form most interesting objects for 

 the microscope. As they are so minute, it is necessary to use a 

 moderately-high power, say \ or -g^th-inch object-glass. It has 

 been estimated that a single head of Comatrichia tijphina * contains 

 a thousand million spores, in addition to those on the delicate 

 network of the capillitium, which forms, as it were, an intricate 

 framework aroimd which the spores are clustered. There are 

 other genera {Reticular ia^ etc.) in which a number of sporangia 

 coalesce so as to form a community of an inch or so in diameter, 

 in which the spores are so numerous that figures fail to represent 

 them. In many species these spores, although so minute, have 

 their walls ornamented. These markings are due to thickenings of 

 the cell-wall, and may consist of dots, warts, spines, or other 

 figures, and they may be either regularly or irregularly distributed 

 over the surface. In other species the walls of the spores are 

 smooth. 



The hair-like threads which form the capillitium present many 

 peculiarities of structure. These are usually so constant, that, 

 next to the colour of the spores, they form the principal basis of 

 classification in modern systems. But even in these there are not 

 always hard and fast lines of demarcation, for some specimens 

 present combinations of character which are assumed to belong to 



* See 'Midland Naturalist,' 1882. 



