92 BOARD OP AGRICULTURE. 



most common among the poorer classes of society, and espec- 

 ially among those who associate most familiarly with dogs, 



Figure 66. 



Figure 67. 



they are by no means confined to them. Many men of great 

 eminence and talent have likewise perished from the same 

 cause. And, unfortunately, society is so constituted that no 

 one can be certain of escaping so long as the parasites that 

 produce the eggs exist in the dogs of every country. It is 

 estimated that 500 persons die annually by this parasite in 

 Great Britain. 



These tumors, in their simplest form, or when young, con- 

 tain a roundish cyst or membranous sac, enclosing a watery 

 fluid, as shown in Figure 66, which represents of natural size 

 a parasite of this kind from the human kidney. More fre- 

 quently the cysts become compound by a process of budding, 

 either upon the outside or inside, or both without and within 

 the membrane of the original cyst, so that its size goes on in- 

 creasing indefinitely, sometimes becoming as large as a child's 

 head, and often completely permeating and destroying the 

 liver, lungs, or other organs. Thus the danger becomes con- 

 stantly greater and greater by reason of the pressure upon 

 and destruction of the adjacent organs. When the budding 

 is external, it results in a cluster of secondary cysts, often a 

 dozen or more, and sometimes hundreds, all more or less con- 

 nected together (Figure 67). And each of the external second- 

 ary or daughter cysts, may increase and multiply itself in the 

 same way, thus, at times, producing many hundreds of other 

 tertiary cysts or " grand-daughter cysts." By internal budding, 



Figure 66 rHydatid or echinococcus cyst, natural size. Hearth and Home, 

 after Thudichum. 



Figure 67. Secondary cysts from a tumor in the liver, natural size. From 

 Cobbold. 



