MALIGNANT DISEASE 555 



in dogs. These have been stated to be sarcomata, but are probably 

 granulomata. 



Malignant disease occurs in all classes of vertebrates, and is 

 generally inoculable on an animal of the same species as that from 

 which it is derived, but not on other animals. The carcinoma of 

 mice has been the subject of much investigation of late. In the 

 writer's opinion, the trend of recent research is to show that malig- 

 nant disease is not due to a micro-parasite, but is derived from the 



FIG. 66. a, Buffer's or Plimmer's body in a cancer-cell ; 

 b, the archoplastic vesicle in spermatid of mouse. (After 

 Farmer, Moore, and Walker.) 



irresponsible division of cells of the normal or of embryonic tissues. 1 

 If there be a parasite, in all probability it is intra-cellular, like the 

 organism of plant cancer (Bacterium tumefaciens) described by 

 Erwin Smith. 2 



The molluscum bodies have likewise been regarded as parasitic 

 (coccidial) in nature, but with them also inoculation and cultivation 

 experiments have failed. The virus is stated to be a filter-passer, 

 as is also the case with bird molluscum. 



Certain malignant-like tumours of birds are also filter -passers, 

 e.g. chicken sarcoma. 



1 For further information consult Pathology, General and Special, 

 ed. 3, R. T. Hewlett (Churchill, 1912). 



2 Trans. XVIIth Internal. Cong. Med. Land., 1913, Sect, iii, pt. ii, 

 p. 281. 



