PELOMYXA PALUSTEIS. 77 



the vacuoles of the endoplasm, most numerously in 

 the central region ; sparingly elsewhere (PL VII, figs. 

 1-3). In examples, say 1 mm. in diameter, there may, 

 Grreeff says, be some hundreds. This author describes 

 them as delicately - walled bodies of globular, more 

 rarely oval, figure, averaging O012 mm. in diameter. 

 Their hyaline contents are pervaded more or less by 

 dark granules; and their position, form, and appearance 

 give in all respects the indubitable impression of cell- 

 nuclei. 



Reproduction takes place by fission, or, as has been 

 more generally observed, by the formation of amoeboid 

 zoospores. The amoebulas, after liberation, pass into 

 a resting state, and ultimately develop a flagellum, or 

 vibratile filament, passing thence into the adult phase. 



Dimensions variable, mature individuals attaining 

 2 mm. diameter (Green ) ; average diameter of a quies- 

 cent individual, exclusive of the pseudopodia, about 

 150 p. 



In the ooze of ponds and ditches, especially such as 

 are partially shaded, in bogs, and amongst Sphagnum 

 in stagnant water ; not very frequent. 



This organism is the largest of the amoeboid rhizo- 

 pods. To the naked eye it is often visible as a speck 

 of semi-opaque matter yellowish brown by trans- 

 mitted light of which the outline undergoes constant 

 change. A pocket lens of moderate power will reveal 

 it with certainty under favourable conditions. 



In her admirable paper in the Linnean Society's 

 ' Journal,' Mrs. Veley (nee Gould) has given the results 

 of some years' careful observations on the physical 

 structure of Pelomyxa palustris. In confirmation of 

 suggestions previously put forward by Prof. Bourne 

 and Dr. Penard, she adduces definite proof of the 

 nature of the rod-like structures. That they are true 

 bacteria is shown (a) by their mobility and division, 

 (b) by their reactions, and (c) by successful culture. 

 They are referable to the genus Cladotlirix Cohn 



