TEXT-BOOK OF BACTERIOLOGY, 361 



The observation of the moulds m unstained condition is simple 

 and fully satisfactory. Since the fungi are nob wet by water, other 

 means must be resorted to in their preparation. We use, for this 

 purpose, 50^ alcohol and add to it a few drops of ammonia. Tear 

 the objects into as minute pieces as possiLle by means of dissecting 

 needles; endeavor to remove the omnipresent air-bubbles, and trans- 

 fer the preparations to glycerin. If it be desired to preserve them, 

 surround the edge of the cover glass with asphalt-lacquer. 



The finer peculiarities of form in the mould fungi can be seen 

 even with moderate magnifying powers. 



The same is true of the oidium and saccharomyces. 



The artificial cultivation of fungi is done exactly as with bac- 

 teria. Moulds thrive better on acid media, gelatin, etc. Sterilized 

 bread-paste is especially favorable for their development. 



Some of these lower vegetable organisms are of importance, as 

 they possess, within certain limits, pathogenic properties. Grohe, 

 in 1870, stated, as a result of a long series of examinations, that 

 rabbits injected with spores of mould fungi (directly mto the blood- 

 vessels) perished in a short time in consequence of an extensive 

 moulding of their internal organs. These observations were de- 

 clared to be -unfounded by many, until Grawitz confirmed them in 

 the most essential points. He started with the view that the mould 

 fungi rarelj'^ make use of their pathogenic capacity only because they 

 first have to become accustomed to a parasitic mode of existence 

 foreign to them. He then endeavored to cultivate them artificially. 



He was apparently successful. By a gradual change of the 

 conditions of nourishment, he prepared the mould-fungi step by 

 step for their new position, and saw small numbers of spores of 

 originally benign moulds killing the test animals. Far-reach- 

 ing conclusions were drawn regarding both the hyphomycetes and 

 the bacteria. 



But the structure built on these conclusions was unsafe. Koch 

 and Gaffky showed that Grawitz had fallen into a quite pardonable 

 error and that his results did not correspond to facts. They as- 

 certained that there are, among the mould fungi, species which are 

 originally and constantly pathogenic. 



This fact has been placed beyond doubt and confirmed by a great 

 number of further investigations, especially those by Lichtheim. 



We now know that definite species among the aspergillese and 

 mucorinese (Aspergillus flavescens and fumigatus, Mucor corym- 

 bifer and rhizopodiformis) can become pernicious to animals. 



By soaking a large quantity of the spores of these fungi in sterile 

 bouillon, straining the cloudy mixture through fine gauze (to keep 



