58 



an E. altricipariens. In this species, although the en- 

 veloping cyst and the mode of annexation of its inner 

 wall to the first vesicle of the Echinococcus are the 

 same, it is distinguished by its greater size. Again, 

 in this form we have not only single scolices or single 

 vesicles, but the production of secondary and tertiary 

 ones (daughter and grand-daughter vesicles), some- 

 times with, and sometimes without, the production of 

 separate scolices, adhering directly to the walls of the 

 vesicles (Kiichenmeister). The scolices thus produced 

 (the mother, daughter, or grand-daughter vesicles) 

 are usually more slender; show marked sucking 

 discs ; have a larger number of hooks (45 to 54 in 

 number), which are more slender than those of E. 

 scolicipariens, and arranged in a double row. 



This scolex is found in various portions of the 

 human body, in the liver, lungs, kidneys, scrotum, 

 sheath of the testis, the spleen, ovaries, breast, throat, 

 in the subcutaneous cellular tissue, and in the bones. 

 It may attain a large size (that of a child's head), and 

 is the cause of the Icelandic disease, the so-called 

 Echinococcus disease. As an estimate of the fre- 

 quency of its occurrence, Dr. Schleissner found in 

 some parts of the island, on an average, two or three 

 members of each family infected ; and Dr. Thornstein 

 says that every seventh man in Iceland has this 

 disease (Weinland). 



The last group under consideration is that of the 

 Acephalocysts ; and, as these are now known to be 

 degenerate or imperfectly developed Echinococci or 

 Cysticerci, we might presume, a priori, that the differ- 



