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XXI. BACTERIA YEAST. 



iodine the rodlets are stained throughout, and very clearly, a 

 brownish-yellow. The figures are thus obtained better than with 

 the other solutions of iodine. The segments of the threads then 

 appear in general shorter than in the fresh state, because all the 

 limits are now visible. In order sharply to differentiate the rodlets 

 we can stain them, according to the methods already known to us, 

 with fuchsin, methyl violet, gentian violet, or Vesuvin, and then 

 keep them as permanent preparations in Canada balsam or in 

 dammar. 



If we focus upon some particular spot in the preparation of 

 pellicle with a magnification of about 1000, we can observe the 

 division (segmentation) of the rodlets direct. It is best to draw 

 the piece of the thread in question at short intervals with the 





FIG. 104. Bacillus subttiis. A , the pellicle (x 500) ; C, spore -formation (x 800). 



camera, and compare the drawings, so as to show the changes 

 which have taken place. If abundant food- stuff is still in the 

 fluid, the individual rodlets divide in every half-hour to an hour 

 and a half. The higher the temperature of the room, the more 

 rapid the division. The rodlets increase in length without be- 

 coming thinner; when they have attained, however, a definite 

 size, a dark-looking partition wall appears across their middle. 

 This process of division explains the arrangement of the rodlets 

 and threads ; it explains also the w r avy course of the threads, 

 which grow at all points by intercalary growth, and, if the ends 

 cannot become farther removed, the thread must become laterally 

 contorted. For this reason, the whole pellicle shows a wrinkling, 

 visible to the naked eye. We next transfer a fragment of the 

 pellicle into a moist chamber, in order to examine it in a sus- 



