22 



Art. 0.— I. Ikeda anil Y. Ozaki; 



Fig 20. 





& / ^.^^ '^' 



■p.c 



r 





t 



\'^' 



and lie as a whole within a 

 tolerably wide cavity (2^.c.) de- 

 veloped around the body of the 

 parasite. This last mentioned 

 cavity, which may bo called the 

 pericyst cavity, is a space in 

 the connective tissue, which no 

 doubt has arisen through a des- 

 tructive disturbance caused by 

 the encysting parasite on the 

 surrounding tissue. The cavity 

 is bordered all around by a 

 more or less dense sheet of the 

 matrix of the tissue. In a later 

 stage of the encystment (the 

 individual U), some of the tissue 

 cells enter into the substance of 

 this bordering wall of the peri- 

 cyst cavity. To this wall as 

 well as to the thin pellicular 

 wall of the organism the cilia are attached with both their distal 

 and proximal ends. It is true, however, that the proximal or 

 inserting ends of the cilia are, in most places of the body of the 

 organism, easily torn off by the knife-blade during microtomishig, 

 as is represented in cyst B. 



At the stage represented by the individual C, the organism is 

 found completely contracted into a roundish body, in the interior 

 of which the original single micronucleus has just started direct 

 division. A little prior to this micronuclear multiplication, the 

 organism secretes the cyst which is often widely separated from 

 the body, as is represented in the figure. The cilia are now 



Four stages of the encystment, conbined for 

 convenience into one figure ; fall explanation 

 is given in the text. Fixed with i^icro-acetic 

 acid solution, sectioned, and stained witb iron 

 hœmatoxylin and orange-G. c, cyst ; rp., inner 

 epithelium of the respiratory tree ; p.c., pericyst 

 cavity ; s.cX., subepithelial connective tissue. 



