254 DISEASES OF TRUE INFECTION. 



The tumors will break down and disappear, but in the bitch 

 they invariably leave a cicatrical contraction so that while the 

 bitch may become pregnant she has great difficulty in parturition, 

 the vaginal walls in that particular portion becoming inelastic. In 

 other cases if the bitch become inoculated by the dog the tumors 

 grow so rapidly that they practically close the vagina so as to 

 produce dystochia. 



That this disease is contagious there is not the slightest doubt, 

 and that it is easily transmitted experimentally has been shown 

 by Washbourn and Smith, who state that, "For the tirst few days 

 after inoculation a swelling can be felt, partly due to the fragments 

 of the tumor introduced, and partly to inflammatory exudation. 

 In some cases this swelling completely subsides, so that nothing 

 can be felt until the appearance of a small nodule indicates that 

 inoculation has been successful. In other cases the swelling 

 persists, and it is difficult to decide whether the inoculation has 

 been successful until a definite increase in the size of the swelling 

 has taken place. The usual time at which there is distinct evi- 

 dence of the first appearance of the growth after inoculation is 

 about three weeks, but it varies between twelve days and a month. 

 * * * The small firm nodules which first appear gradually 

 increase in size, and form rounded lobulated masses. At the com- 

 mencement they are freely movable beneath the skin, but at a 

 later period the latter become thinned out, of a bluish-red colour, 

 and firmly adherent to the growths. * * * rpj^^ maximum 

 growth is attained in about three months. A curious regularity 

 obtains in this respect. * * * Having reached this stage, retro- 

 grade stages are not long in appearing; the growth becomes soft 

 and fiabby, and slowly dwindles until nothing is left to indicate 

 its former presence. * * * j^ ^^^^^^^ ^^^^ ^-^e cases the sub- 

 sidence of the tumour was accompanied by ulceration ; the thinned- 

 out reddened skin giving way over the growth, which has pre- 

 viously undergone softening, and there results a deep ulcer, from 

 which a thin grumous discharge fiows. Even when these retro- 

 grade changes are occurring, fresh growths occasionally take place 

 at the periphery of the tumour." 



Clarke, who has carefully examined the tumors, likens them to 

 the alveolar sarcoma of the human breast and classes them as 

 granulomata. He describes these stages and shows marked changes 



