ACTINOMYCOSIS. 439 



that time considered the cause. This fungus was observed in these 

 tumors as early as 1860 by Rivolta, and by others subsequently, with- 

 out havdng been suspected as causing them. 



Since Bollinger's publication much work has been done, many 

 observations made, and many hitherto obscure disease processes 

 brought into relation with this fungus. Furthermore, a similar dis- 

 ease in man was first definitely shown to be associated with the same 

 fungus in 1878 by Israel, and in the following year Ponfick pointed 

 out that the disease described by Bollinger in animals and that 

 found by Israel in man were due to the same cause ; that is, that the 

 fungi described by these observers were one and the same. 



The tumors and abscesses wherever they may be are all found to 

 be the same in origin by the presence of the actinomyces fungus. 

 When they are incised, a very close scrutiny with the naked eye, or, 

 at most, a hand lens, will reveal the presence of minute grains which 

 vary from a pale-yellow to a sulphur-yellow color. They may be 

 very abundant or so few as to be overlooked. They are embedded 

 in the soft tissue composing the tumor or in the pus of the abscess. 

 With a needle they are easily lifted out from the tissue, and then they 

 appear as roundish masses about one-half millimeter (5^ inch) in 

 diameter. To anyone familiar with the use of a microscope the 

 recognition of these grains or particles without any previous prepa- 

 ration is a comparatively easy task. 



When examined in the fresh condition under a microscope magni- 

 fying up to 250 diameters the general structure is made out without 

 much difficulty. These grains consist of collections of minute, round- 

 ish masses. Their outer surface is made up of club-shaped bodies all 

 radiating from the center of the mass (see PI. XXXIX, fig. 2), some- 

 what like a rosette. If the fungus is crushed, the interior is found 

 made up of bundles of very fine filaments, which are probably con- 

 tinuous into the club-shaped bodies. The addition of a dilute solution 

 of caustic soda or potash greatly aids the examination, as it re- 

 moves the layer of cells adhering to the fungus, which obscures the 

 structure. Now and then these grains are found to be in a calcified 

 condition. The exterior is incrusted in lime salts, which are dis- 

 solved by adding some weak dilute acid, like acetic acid. Only by 

 this procedure can the fungus be definitely recognized when in a 

 mummified condition. 



These are the bodies whose presence causes sufficient irritation in 

 the tissues into which they find their way to set up inflammatory 

 growths. These growths increase as the fungus continues to multiply 

 until they reach enormous dimensions, if the affected animal is per- 

 mitted to live long enough. The true nature of this parasite is not 

 yet definitely settled, although many excellent observers have occu- 

 pied themselves with it. According to earlier observers, it is a true 



