30 Transactions of the Society. 



the soil or in food-substances, which can be sprinkled over the 

 surface of the gelatin, and the colonies which develope studied as 

 already described. 



Lastly, if these biological appearances may be taken with 

 other characteristics into consideration in the determination of 

 species, we have a basis for a classification of bacteria into species, 

 of which at present we stand in need. 



These methods of artificial cultivation assist us also in deter- 

 mining the position in the scale of fungi of certain micro-organisms 

 which is at present doubtful. In illustration of this, and in order 

 to bring to your notice the specimens before you, I shall, in con- 

 clusion, say a few words with regard to the fungus Actinomyces. 



Actinomycosis is a disease occurring not uncommonly in cattle, 

 but very rarely in man. For the accounts of it, we are indebted 

 chiefly to the writings of Bollinger, Israel, and Ponfick. The 

 disease is caused by a parasite known as Actinomyces, or the " ray- 

 fungus." The parasite appears in the form of a rosette, composed 

 of club-shaped elements, and these rosettes are colourless or of a 

 yellowish or yellowish-green tinge, and visible to the naked eye. 



The fungus is believed to gain an entrance to the animal by 

 the mouth, being taken in with the food, possibly through the 

 medium of a wound of the gum, or a carious tooth. In whatever 

 manner it has gained access to the living organism, it sets up infla- 

 mation, resulting in the formation of a new growth, composed 

 chiefly of round cells, which resembles a tuberculous nodule. These 

 nodules may break down and suppurate, or they may go on 

 increasing in size ; fibrous tissue developing between the nodules, 

 large tumours eventually result, containing purulent cavities and 

 excavations. In the slimy detritus, the little pale-yellow grains 

 of fungus can be detected. In cattle, the lower jaw is usually 

 affected, and then the upper jaw and neighbouring parts. The 

 organism may also occur in nodular tumours of the pulmonary, 

 subcutaneous, and intermuscular tissue ; it is the cause of " wooden 

 tongue," and has also been variously described, before its true nature 

 was understood, as bone-canker, bone-tubercle, osteo-sarcoma. 



In man the pulmonary formations tend to break down early, 

 forming fistulse and sinuses, with the clinical characters of empyema. 

 In one case, there were symptoms of chronic bronchitis with foetid 

 expectoration. In other cases, the disease originating in the lung, 

 spread to the prsevertebral tissues. If the fungus attacks bones, 

 it produces caries. This has been observed to occur in the bodies 

 of the vertebrae. In another group of cases, the disease has 

 been described as commencing in the intestinal canal. The 

 parasite has also been detected in the crypts of the tonsils of 

 healthy pigs, and a similar, if not identical, fungus in a diseased 

 condition of the spermatic duct of the horse. The disease has been 



