8o 



HARDWICKE'S SCIENCE-GOSSIP. 



small group that are like the reed mace (Typha) in 

 miniature. These may either be grouped, like a tiny 

 forest, with separate stems and closely-compacted 

 he.ids (Stemonitis), each head composed of an in- 

 tricate network of most delicate threads, or both 

 stems and sporangia may stand singly (Comatrichia). 



A very abundant and generally distributed genus 

 has bright yellow spores (Trichia) and capillitium. 

 This network or capillitium was called "wool" by 

 some of the descriptive botanists of last century, and 

 it certainly has a strong resemblance to a tiny tuft of 

 woolly fibre when seen projecting from the ruptured 

 capsules. These may often be observed in compact 

 groups of an inch or two in diameter, on rotten tree- 

 stump;, or scattered over the foliage of mosses, and 

 liverworts that 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. 



Yet another group, that 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 (Arcyria). 



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 is 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, so that the contents of 

 the sporangia are only spores. But even . these in 

 some cases have a delicate framework (Cribraria) 

 which lines the wall of the sporangium and gives it 

 support. At first this external skeleton may be mis- 

 taken for a true capillitium, and hence may deceive 

 the novice as to the true position in classification of 

 the species under consideration. Close observation 

 will, however, soon enable the observer to distinguish 

 between these two organs. 



The contents of the sporangia form most interest- 

 ing objects for the microscope. As they are so 

 minute it is necessary to use a moderately high 

 power, say, \ or gth inch object-glass. It has been 

 estimated that a single head of Comatrichia typhhia* 

 contains a thousand million spores, and these are in 

 addition to the delicate network of the capillitium 

 that forms, as it were, an intricate framework around 

 which the spores are clustered. There are other 

 genera in which a number of sporangia coalesce so as 

 to form a community (Reticularia) 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 orna- 



* See " Midland Naturalist," iSS;. 



mented. These markings are due to thickenings of 

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

 or other figures, and may be either regularly or 

 irregularly distributed over the surface. In other 

 species the walls of the spores are smooth. 



The hair-like threads that 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 that are 

 assumed to belong to closely-allied species. These 

 threads may be simple or branched ; combined into 

 a network, or have numerous free ends, and they 

 may be united to the walls or to the central columella. 

 Their ornamentation is often very beautiful, and of 

 most intricate designs. These markings may consist 

 of spirals, spines or cogs, and are due to external 

 thickenings of the walls. In this respect they differ 

 from the elaters of Jungermannire, which have the 

 spirals coiled up in the interior of the cells. Some 

 few species show affinities with mosses in the posses- 

 sion of an operculum ; others approach the fungi, 

 through the Lycoperdons, in the presence of a capil- 

 litium, and the whole group exhibits a relationship 

 with the animal world, by the motile amceba-like 

 cells, which precede the formation of the Plas- 

 modium. 



The student of the mycetozoa would find a peculiar 

 fascination in the subject as his knowledge of it 

 increases, and as it is comparatively " An Open 

 Field," he would find plenty of opportunity for original 

 research. Nor need his observations be limited to 

 any one period of the year, as they are to be found 

 at almost all seasons, extreme of heat and cold being 

 most detrimental to their development. The pursuit 

 would lead him into some of nature's quietest haunts, 

 and also furnish him with material for the most ad- 

 vanced microscopical investigation. 



Possibly it may not be presumptuous to assume 

 that some of our readers will be stimulated to com- 

 mence the study of the subject. A difficulty would, 

 however, present itself to the mind of the novice, as 

 to how his specimens are to be named. It would be 

 perilous to invite correspondence, fearing a deluge, 

 but, so far as possible, assistance would be cheerfully 

 rendered to any who 'may wish to form a practical 

 acquaintance with the Mycetozoa. 



For those who wish to pursue the subject further, 

 reference is made to the following literature :— 



"Mycetozoa," "Midland Naturalist," vols, from 

 1882, 1887, 1888. 



" Myxomycetes of Great Britain," Dr. M. Cooke, 

 1877. "An Open Field," "Nature Notes," Mr. 

 A. Lister, January, 1892. "Notes on Mycetozoa," 

 "Journal of Botany," Mr. A. Lister, September, 1S91. 

 " Myxogastres," Mr. Geo. Massee, 1892. 



Luton. 



