200 PROTISTS AND DISEASE 



of a fully-developed molluscum-tumour, such as that shown 

 in Part IV, Plate III, after allowing for the loose parasites 

 that have been detached in mounting the section, we can 

 compute the proportion of parasites to host-tissues as rather 

 more than 1 to 2. 



In the section of the mammary sarcoma, Part III, Fig. 32, 

 we see that the proportion of parasites to host-tissue is 

 again something near 1 to 2 ; and again in the squamous- 

 celled cancer of the nasal septum as illustrated in Plates IV 

 and V, Part III, we see again about the same ratio holds 

 good. As I stated in 1892 about one third of the weight of 

 rapidly-growing cancers is accounted for by the visible 

 parasites present in them. 



Can we name the parasite of cancer ? We must first 

 consider the transformation of late syphilis into cancer and 

 reflect that in some cases we shall probably be naming 

 Cytoryctes luis over again. 



By their particular harmony with the host-cells and 

 tissues the parasites produce the anatomical varieties of 

 malignant tumours. Some of these tumours have features 

 so pronounced that a brief inspection by the microscope 

 enables the pathological diagnosis to be made ; in others, 

 again, only after careful study can a decision be reached ; 

 and, in not a few cases, it is impossible by the microscope 

 alone to distinguish between cancerous and syphilitic or 

 other inflammatory processes. 



In general, however, we can recognise a special setting 



