17.6 



DEPARTMENT OF AGRICULTURE. 



spirit lamp or candle close to the vein, withdraw the point of the tube 

 directly from the vessel into the flame, and hold it there until sealed. 



If the oi^eration has been properly performed, and the blood be healthy, 

 it will coagulate and then remain unchanged for an indefinite i)eriod. 



Exudates in the pleural or peritoneal cavities, bile, urine, «&c., are 

 obtained and preserved in the same way. 



The next step is to place the material thus obtained in favorable con- 

 ditions for the growth and development of any fungus germs which it 

 may contain. The requisites for this purpose are warmth, moisture, a 

 supply of nutritive material, and exclusion of foreign spores. 

 With regard to this last point, we reasoned as follows : 

 By no amount of precautious or of complexity of apparatus is it possible 

 to secure such absolute isolation of a fragment of tissue or a quantity of 

 blood from possible contact with foreign spores, that the results obtaiued 

 from its cultivation can be considered as positively conclusive. By no 

 meaus 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 atmos- 

 phere 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 (b'uwn. It 

 was felt, therefore, that to adopt at the outset extraordinary precautious 

 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. 



Let us first see, we argued, whether, without taking special pains to 

 prevent the entrance of extraneous matters, the tissues and fluids of a 

 diseased animal will produce fungi which healthy tissues and fluids 

 placed side by side with them will uot. The apparatus employed con- 

 sisted of the following : 

 1st. The so-called " isolation apparatus." 



This consists of a thin flat-bottomed flask of from four to eight ounces 



capacity, closed by a cork dipped in parafiQn. 

 Through the cork passes a glass tube bent 

 twice at right angles, reachiug about two 

 inches into the flask, and having the exter- 

 nal end loosely closed by a pledget of dry 

 cotton or jewelers' wool. (Fig. 15.) 



This is used in operating upon consider- 

 able quantities or masses of material which 

 are to remain undisturbed for several days, 

 weeks, or months. 



To follow out the changes which occur 

 from day to day, and especially to trace 

 under the microscope the conunencemeut 

 and progress of any fungus growth, grow- 

 ing slides of various patterns, and the so- 



Fig. 15. 



