CYSTS. 



85 



mulatioii of fluid tends to transform the cavity in whicli it is 

 contained, whatever its original shape, into a sj^here (fig. 32). 

 Before retention begins the inter-papillary spaces exhibit, on trans- 

 verse section, triangular and four-cornered figures with incurved 

 sides and very acute angles, figures such as necessarily follow 

 from the apposition of cylindrical bodies. As the fluid accu- 

 mulates, the acute angles open out. They pass through a para- 

 bolic into a simple curve. The inflexed sides, for their part, are 

 gradually depressed till their convexity is quite eftaced ; and 

 these two sets of movements co-o])erate to give the space a cir- 

 cular fiorure when cut across — the cavitv l3ecomes orlobular. 



It would lead me too fiir were I to attempt in this place to 

 give a detailed analysis of the physical law which governs this 

 series of phenomena. I will content myself with reminding the 

 reader that of all stereometric bodies the sphere is that in which 

 the capacity is greatest in proportion to the area of its surface. 

 .80 long, therefore, as the contents of a body continue to increase 



Fig. 32. 



Papilloma cysticum from the portio vaginalis, showing conver- 

 sion of inter-papillary fissures into retention-cysts. 



in amount, without any corresponding extension of its internal 

 surface, the body must necessarily tend to assume a spherical 

 form. The present is a case in point. I may add that the 

 principle which we have just seen illustrated by a single example 

 is one of very frequent application in the organism. I need 

 only allude to the shape of the eye, of the urinary and gall- 

 bladder, of the heart, &c. 



