LUENCE or NUTRITION o.\ GROWTH 133 



The walls of the mother-cell swell up, the chain ifl (3 and the 



thereby liberated. Some facts indicative of their pout, 



influences have been gum in a previous section (;.; 5 :;). The Bpore membl 



capable of swelling up, so that, when I i are placed in water earh of them 



soon appears to be .Mirrounded by a dull halo the swollen external la\er of the 



membrane. 



$ 109. Influence of the Mode of Nutrition on the Form of Growth. 



This factor was exhaustively described, for the bacillus in question, by I 

 III t IINKR (I V.). A few of the forms of growth observed an; shown in Fig. 42, 

 r.\- employing a faintly 

 alkaline 5 per cent, solu- 

 tion of meat extract, 

 rods (as at in) are ob- 

 tained, 0.5/1 broad and 

 6-10 p. long. If a neutral 

 solution of 5 per cent, of 

 sugar and o.i per cent, 

 of meat extract be taken, 

 then the forms shown in 

 2 appear, viz., short rods 

 0.8 p. broad and only 4-6 

 p. long. Finally, in an 

 infusion prepared from 

 hay in which woody 

 stems predominate, the 

 cells (3) have a length 

 of 12 n and a breadth 

 of i.o p.. Under all the 

 above conditions repro- 

 duction goes on with 

 vigour, the fission being 

 very rapid. The new 

 partition walls formed 

 during the operation are 

 at first so thin and so 

 faintly refractive as to 

 escape the eye in the case 

 of unstained prepara- 

 tions. If, however, a solu- 

 tion of iodine be added, 

 then the apparently 

 uniform long cells are 

 seen to be divided into 



short cells in the manner 



d i ag ram mat i c a 1 1 y 



sketched at /> and c in the 



figure. All these shapes 



belong to the cycle of 



normal forms of growth, of strong vitality, and capable af reproduction. When. 



however, the composition of the nutrient solution is, from the first, unfavourable 



(/.'/ :i solution of o.i percent, of asparagin or albumen, and 10 per cent, of siiyar), 



or becomes so subsequently in consequence of the excivtien of injurious waste 



Fie. 42. IJarillus sulitilis under various nnnlit ions of rulliva- 

 tlon. Kor f\p!:iii:ilioii >cr tf.xt. .Mii-ii. iiliout 4000. (.///</ 

 //. A' it, Inn- 1- . i 



