EXPERIMENTS WITH CRYPTOGAMIC GROWTHS. 157 



if, under such circumstances, a mold or mildew appears upon the suspected matter, the argu 

 ment is that such mold necessarily sprung from the micrococcus granules as its parent germs, 

 and therefore represents the perfect fungus of which such micrococcus is a special form. 



Now, since the spores of the common molds are almost omnipresent, the conclusive- 

 ness of all such experiments must depend upon the possibility of showing that all extrane 

 ous 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 at 

 tempting a similar line of research. 



The first thing to be done is to obtain the suspected fluids in a state of purity, with 

 out 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 effect this we take a glass tube about three-sixteenths of an inch in diameter, seal 

 one 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, (a.) 



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 f/ 



the requisite heat is obtained the slender neck is - 

 rapidly drawn to a point and sealed. We now 

 have a pointed, hermetically-scaled tube, (b,) in 



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

 been destroyed. 



This we call a &quot;vacuum tube.&quot; 



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 

 pointed end of the tube and break it off within the vein, pressure being at the same time 

 made upon the vessel from above and below toward the opening by the fingers of an 

 assistant. 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 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 operation has been properly performed, and the blood be healthy, it will coag 

 ulate and then remain unchanged for an indefinite period. 



Exudates in the pleural or peritoneal cavities, bile, urine, etc., are obtained and pre 

 served in the same way. 



The next step is to place the material thus obtained in favorable conditions 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 precautions 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 obtained from its cultivation can be considered as posi- 



