PLASSOMYXINEAE 



things ; that is when we place them suitably in water, thus 

 using the experimental method. 



Those observers who have studied lesions in their earliest 

 stages have found that the first site of the parasite is inside 

 the host-nucleus, and its escape into the cytoplasm has been 

 seen. Some subsequent 

 stages are shown below ' ,v 



in Fig. 30. 



Cultures. When we 

 are planning experiments 

 to decide whether any 

 object is alive we must 

 first consider the con- 

 ditions in which it is 

 found in nature. 



The earliest stages of 



Plassomyxa contaqiosa as ^ ^ 



FIG. 27. MOLLUSCTJM BODIES AND SQUA- 



seen in sections of the MOUS EPITHELIAL CELLS. From a teas- 

 ing of a freshly excised nodule smeared 

 on a slide and fixed with perchloride 

 of mercury solution and mounted in 

 glycerine and water. Drawing eye-piece. 





X 400 diams. From Part IV. 



tumour are found inside 

 other cells, hence in anae- 

 robic conditions : the ripe 

 parasites on the contrary 



are extruded from the body and their subsequent develop- 

 ment is most likely to be both aerobic and aquatic, the 

 latter probability being supported by the observation that 

 the disease is sometimes contracted in Turkish baths. 

 Aerobic water-cultures are thus indicated. Seeing that we 



