INVESTIGATION AS TO ORIGIN OF CATTLE DISEASES. 175 



talile ill tlieir nature, as being developed from and capable of reproduc- 

 ing certain common fungi, popularly known as rusts, smuts, or molds. 

 To prove tlie truth of the latter .statement, experiments have been 

 made by various investigators on the principle of placing the fluids con- 

 taining the micrococcus in the proper conditions as regards warmth and 

 moisture for the development of fungi; supplying the germs with suita- 

 ble pabulum for their nourishment, and adopting such precautions as 

 are possible against the fortnitous introduction of spores of fungi from 

 the atmosphere. And if under such circumstances a mold or mildew 

 appears upon the suspected matter, the argument is that such mold 

 necessarily sprang from the micrococcus granules as its parent germs, 

 and therefore represents the perfect fungus of which such micrococcus 

 is a special form. 



Xow, since the spores of the common molds are almost omnipresent, 

 the conclusiveness of all such experiments must depend upon the possi- 

 bility of showing that all extraneous bodies have been perfectly excluded 

 from the fluids cultivated. 



in detailing our own experiments in this direction, therefore, we give 

 a somewhat minute description of the apparatus and processes employed ; 

 partly that the value of the results obtained may be judged by it, and 

 in part because it may be of use to others attempting a similar line of 

 research. 



The first thing to be done is to obtain the suspected fluids in a state 

 of purity, without risk of contamination by spores floating in the 

 atmosphere, and in such a manner that they can be preserved for some- 

 time without risk of material change. 



To eftect this we take a glass tube three-sixteenths of an inch or so in 

 diameter, seal oue end by the flame of a lamp, and, at a point about three 

 inches from the sealed end, draw it out to a slender tube. (Fig. 14-rt.) 

 The tube is then held nearly upright in the flame of a Bunsen burner 

 until the whole of the sealed end up to the narrow neck is red hot. The 

 part in the flame is held with pincers, the other end in the fingers, and 

 when the requisite heat is obtained the slender neck is rapidly drawn to 



a point and sealed. We ^^ -~ ~— ^ - ^ — ) 



now have a pointed, her- , 



nietically- sealed tube, ^ _...== — ' 



(Fig. 14-?^,) in which there Fig. 14. 



is a partial vacuum, and in which by the red heat all organic matters 



have been destroyed. 



This we call a " vacuum tube." 



Suppose, now, that we want some blood for experiment. As soon as 

 possible after the death of the animal, lay bare the jugular vein, prick it 

 with a lancet, introduce the i)uiuted end of the tube and break it oft" 

 within the vein, i^ressure being at the same time made upon the vessel 

 from above and below towards the opening, by the fingers of an assist- 

 ant. The blood will rush into the tube, and if it has been properly 

 made, will fill it for three-fourths of its length. Then, holding a lighted 



