950 
Notes. 
were found. The growths on the earth were better marked than those on the roots, 
and varied from small flat, whitish films to patches 8 mm. square and up to 4 mm. 
in height. The latter were amorphous masses of Bacteria which cultural and micro- 
scopical methods showed to be B. megatherium in a practically pure condition. The 
vitality of the growths was well marked during the late winter months, during which 
I easily obtained typical and rapidly growing cultures on agar-agar and gelatine. The 
greatest efflorescence was attained towards the end of spring. Later on the growths 
looked drier and more scanty, their creamy colour becoming dead white, and they did 
not flourish so readily on culture media. At this stage more spores than bacilli were 
observed in both growths than in the period of greatest development. The chalky, 
desiccated appearance, poor reaction to cultural methods, and preponderance of spores 
were intensified during the summer. 
As a site for Bacteria the roots of the palm would not be unusual, but well- 
marked and diffuse bacterial growths on the surface of the earth are unique and less 
easy to account for. Although Bacteria are found plentifully in the upper six-feet or 
so of undisturbed soil (not deeper, unless corpses or other sources of pollution exist 
below), 1 a well-defined positively aerotropic growth, even of aerobes, is not seen. 
The only exceptions seem to be the Myxobacteriaceae described by Thaxter, 2 which 
are found on various animal excrementa, and exhibit Myxomycetes-like fructifications. 
Their nutritive conditions are, therefore, eminently favourable. Whether this may 
help to account for their specialized fructification is problematical, but there is no 
doubt that the question of nutrition exerts an important effect on the exuberance to 
which a bacterial development will extend, and I was inclined to attribute the peculiar 
efflorescence of Bacillus megatherium on the earth to some unusual source of nourish- 
ment, which with the favourable temperature of the plant house (average 8o° F.) would 
conduce to free development. The interest of the conclusion that the earth-growth 
existed saprophytically on the persisting remains of products of the decayed wood in 
the earth was minimized by later observations. On the open, horizontal surfaces of 
the boxes and tubs in which other tropical plants were placed, I afterwards noticed 
several growths of the bacillus. Here the areas were mostly circular in outline. The 
smaller ones were flat, the larger somewhat raised, particularly towards the centre, and 
measured up to an inch in diameter. In these situations the existence of a marked 
supply of food material is not so obvious. I hope to note any gradual change from 
a flat film to raised growths like those on the earth around Demonorops which appear 
to connect the ordinary free living Bacteria with the more highly specialized fructifica- 
tions of the Myxobacteriaceae. 
J. CHARLES JOHNSON, M.A., M.Sc. 
University College, 
Cork. 
1 Young : Proc. Roy. Soc. of Edin., xxxvii, Part IV, p. 759. 
2 Thaxter : Bot. Gaz., xiv, 1892, p. 389 ; xxiii, 1897, p. 395; xxxvii, 1904, p. 405. 
