$in.] Endosporous Bacteria. 21 



B. Megaterium (Fig. i) and B. subtilis (Fig. 2, B)] the trans- 

 verse rent either extends quite across, so that half the membrane 

 is placed like a cap on each extremity of the cell, or the halves 

 remain attached on one side, so that the growing cell must 

 emerge from a gaping cleft (Fig. i , h-f). The ruptured mem- 

 brane is usually delicate and pale. In B. subtilis only it retains 

 at first the lustre and dark outline of the spore before ger- 

 mination, and hence it is probable that these phenomena have 

 their origin in the membrane. Sooner or later the membrane 

 thus torn from the cell swells and disappears. It may be owing 

 to the very early period at which the swelling sets in that 

 sometimes, as, for example, in B. Megaterium and B. Amylo- 

 bacter, the removal of the membrane is not perceptible in one 

 germinating spore, while it is clearly seen in others, and that in 

 other species, as in B. Anthracis, no removal of the membrane 

 takes place at all. 



The longitudinal growth of the first cell in germination has 

 always the same direction in space as the longitudinal axis of the 

 spore or spore-mother-cell. This is the case also in Bacillus 

 subtilis, which appears at first sight to behave differently in this 

 respect. In this species the first rod-shaped germ-cell usually 

 emerges from the open transverse rent in the spore-membrane 

 in such a manner that its longitudinal axis crosses that of the 

 spore at a right angle, but this is not caused by a corresponding 

 divergence of the longitudinal growth, but by the circumstance 

 that when the germ-cell has attained a certain length it bends 

 through about 90, and thus projects on one side at a right 

 angle from the rent in the membrane. The bending of the 

 germ-cell is evidently caused by the resistance offered to the 

 elongation of the cell by the spore-membrane, which in this 

 species is highly elastic and is always ruptured on one side. 

 When growth is very rapid the two extremities of the young 

 rod may remain fixed in the membrane, and in that case the 

 middle portion projects in a curve from the aperture. It is not 

 till a later period, when the rods have begun to divide and 



