20 Cultivation of Microscopic Fungi. [""Zmlx^i'n^iX^ 



a quantity of blood from possible contact with foreign spores, that 

 the results obtained from its cultivation can be considered as posi- 

 tively conclusive. By no means known to us can a piece of lung be 

 transferred from the body of an animal to the interior of a glass 

 flask, without contact with the atmosphere and with instruments, 

 nor even with the more manageable blood can we be absolutely 

 certain when we see its surface covered with mold, that the possibly 

 single spore from which that forest sprang must infallibly have 

 been in the vein of the animal whence the blood was drawn. It 

 was felt, therefore, that to adopt at the outset extraordinary pre- 

 cautions against the introduction of foreign spores, would be more 

 apt to lead to error than even taking none at all. The method of 

 comparison was therefore resorted to." Thus healthy and diseased 

 tissues and fluids were similarly treated, using ordinary precautions. 



The " isolation " apparatus they adopted is a thin, flat-bottomed 

 flask, with a cork dipped in paraffin at the neck, pierced for a 

 tube bent at right angles, closed at the outer end with a plug of 

 fine cotton wool. 



The culture apparatus used was a large flat glass cell, contain- 

 ing a porcelain stand, rather higher, wliich supports a glass shelf 

 for holding the slides and watch-glasses for daily examination, this 

 covered by a glass bell jar closed at the neck by a cork dipped in 

 paraffin, through which is passed a right angle bent tube, the 

 outer end plugged with cotton, and the interspace between the 

 outer cell and glass jar filled with a strong solution of permanganate 

 of potash. These somewhat, as stated, resembling Hallier's, but no 

 means were added for drawing fresh air into the vessel. 



The growing slide recommended is the ordinary 3x1 inch slide, 

 having " a piece of thin, fine, white blotting-paper of the same size, 

 with an oj)ening in the centre three-fourths of an inch in diameter, or 

 a little less than that of the thin glass cover used. The edges of the 

 paper may be cemented to the glass with a little Canada balsam, 

 although this is not necessary. To use it, put it in strong alcohol 

 for ten minutes, then in distilled water for the same length of time ; 

 free the central opening from water ; place in it a drop of the fluid 

 to be cultivated, and cover it with a thin glass cover." It is to be 

 kept flat and set in a culture apparatus : when " water alone is 

 used as the isolating fluid," a piece of sewing-thread rests on one 

 end of the slide, the other end dipping into the water. If not to 

 be set in a moist chamber, the paper is covered with a correspond- 

 ing " piece of thin sheet rubber or oiled silk," with a similar cen- 

 tral aperture. If the fruit is to be developed, " a groove should be 

 cut in the paper to the edge of the slide " to admit air. A very 

 ingenious form of development apparatus used was a glass beaker 

 containing a little water, closed at the top by a thin sheet of rubber 

 having suspended from its centre, by a thread, " a strip of thin 



