FUNGI. 305 



by stretching and squeezing to a film not exceeding 

 a 250th or a 300th of an inch thick, cover with thin 

 glass, press steadily, and view with a high power, 

 using the achromatic condenser and a small stop. 

 An immense quantity of little thread-like bodies will 

 then be seen ; and, if the power be sufficient and the 

 illumination carefully adjusted, a beaded form will 

 appear sufficiently often to indicate the class of object 

 to which they belong. That the little bacterium 

 bodies have not been obtained by tearing big ones 

 to pieces in the stretching process will be plain upon 

 examination of the plant in different conditions of 

 extension and thickness. I have employed in this 

 investigation Smith & Beck's one-twentieth and 

 second eye-piece, giving a magnification of 1750 

 linear. A minute drop of solution of iodine, followed 

 by another minute drop of dilute sulphuric acid, 

 facilitates the view of the beaded structure. The 

 bacterium bodies probably give rise to the tough 

 mucus in which they arc involved, and the unorga- 

 nized mass in which they are embedded in the 

 vinegar-plant may only differ in density from the 

 more delicate material in which the same kind of 

 bodies are enveloped when they form a pellicle on 

 the surface of infusions, or adhere in a more or less 

 globular shape. The yeast-plant is shown to be 

 intimately connected, if not identical with, several 

 vegetable forms to which distinct names have been 

 assigned ; but both upon botanical and chemico- 

 physiological grounds, it would be very interesting 

 to ascertain to what extent that form of it known as 

 the vinegar-plant is associated with bacterium bodies. 



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