Contagious Diseases of Insects. 303 



somewhat ropy appearance when shaken. The check flask was 

 perfectly clear. On September 8 the infected infusion was 

 covered with a thick white surface-scum and the whole mass of 

 the fluid was strongly turbid. A droplet of the liquid contents 

 was now drawn out for examination, with a freshly-made capil- 

 lary tube pushed down through the plug. The thin film upon 

 the slide was milky with bacteria, which presented, under the 

 microscope, an appearance of double ovals with occasional 

 small clusters or patches of the same object, and occasional 

 strings of three. No other form was seen among myriads 

 passed under the eye, and no flagellate motion was detected ; this 

 was, consequently, an unmistakably pure culture of this single 

 organism. Admirable slides of this material, prepared at this 

 time, further illustrate the purity of the culture, and show that 

 many, perhaps all, of the so-called "double ovals " of my notes 

 were immature Bacillus intrapallens, in most of which the pale 

 center was but just beginning to show. On the 13th of Sep- 

 tember a number of additional slides were made from this same 

 flask, the* contents of which were now extremely turbid, the 

 lower half thick with a whitish sediment, and the surface and 

 the flask about the edges covered with a scum. These slides 

 contain only the above Bacillus, somewhat increased in size, and 

 showing the characteristic pale center more distinctly. Con- 

 sidering the frequency with which this form occurred in the 

 dead Datana larvae of this lot, I have no doubt that this was a 

 successful culture of this particular Bacillus. 



On the 17th September these fluids were selected for an 

 experiment intended to test the possibility of preserving 

 throughout the winter the bacteria contained in them, and a 

 number of films were spread upon glass slides previously steril- 

 ized by heating, dried immediately with moderate warmth, and 

 laid away for preservation. At the same time small glass 

 tubing was taken, heated thoroughly in the flame of a lamp, 

 and divided by melting, while still almost red hot, into short 

 tubes closed at both ends. As soon as cooled, these partially 

 exhausted tubes were first filled with the bacterial culture by 

 breaking off beneath the fluid, with sterilized forceps, the tip 

 of the tube, which then filled by atmospheric pressure; and 

 were then immediately re-sealed by heat and laid away in 



