PHYSIOLOGY OF THE SULPHUR BACTERIA. 373 



small scale in the laboratory, by placing a certain quantity of the 

 black mud in suitable vessels containing water, and then leaving 

 the whole to stand uncovered. We will not go further into the 

 matter of the rise and fall of the bacterial plane as observed by 

 him, because BEYERINCK (I.) had made similar experiments two 

 years earlier, and applied to the phenomenon a term (Balderien- 

 Niveau) having the same significance as that used by Jegunow. 



csu^WWi 



FIG. 80. A portion of the bacterial plane from the preced- 

 ing Fig. showing the arched construction of the plane 

 itself, as well as four of its fountains. Magn. n. 

 (After Jegunow.) 



FIG. 79. Culture of Sulphur Bacteria from the Limanes(in a small vessel ; reduced scale). 



The figures on the label give the dimensions, the thickness of the layer of liquid being 

 0.9 m.m. The bottom is occupied with black Limanes rmid ; above this is the liquid, 

 the meniscus of which is visible at the top of the Fig. ; and in between is the bacterial 

 plane with five " fountains." (After Jegunow.) 



The discoveries made by JEGUNOW (II.) with regard to the 

 construction of this bacterial plane, in the case of the organisms 

 now in question, must, however, be considered as novel. When 

 cultivated in higher and broader, but thinner, strata of liquid, the 

 plane assumes the form reproduced on a reduced scale in Fig. 79, 

 i.e. the bacteria do not form a simple plane, but become piled up 

 in places into tuft-like projections each about 3-4 mm. long 

 four of these being shown (enlarged) in Fig. 80. The examina- 



