196 PROTISTS AND DISEASE 



and other exclusive forms as the only parasitic protozoa in 

 cancer has really kept back the recognition of the nature of 

 the disease." 



Instead of the word " protozoa " in the foregoing extract 

 I should now write " protists." 



Sporangium-formation in cancer. Although seen only 

 occasionally in sections of cancer sporangia are quite un- 

 mistakable, as shown in Fig. 58. 



Such definitely encapsuled structures do not occur in 

 normal human tissues ; the definite chromatin bars seen in 

 some of the subdivisions of Fig. 57, 7, show that the process 

 is not one of degeneration. By study of even some single 

 sections of this tumour such sporangia were seen to be the 

 end of a series of phases of which the earliest are intranuclear 

 bodies in the plasson state. 



Alternative modes of reproduction in cancer-parasites. 

 In very rapidly-growing squamous-celled cancers the para- 

 sites instead of growing for a time in the plasson state, 

 divide by mitosis as soon as they escape from the nucleus in 

 the same way as some of those of the mammary sarcoma 

 described above, and those of the last stage of the infective 

 sarcoma of dogs described in Part II. 



To take one instance : At the Hampstead General 

 Hospital a cancerous gland was removed from the left 

 parotid region of a woman aged seventy-one years. The 

 patient had been operated on four months earlier for a 

 growth below the left eyelid, and the pathologist had 



