88 BOARD OF AGRICULTURE. 



of rabbits, and in squirrels, and other animals, so that dogs 

 may perhaps obtain the same tape-worms by eating rabbits, and 

 then give the "water-brain" in turn to lambs. But the. 

 coenurus-like cysts of rabbits, etc., may prove to be a distinct 

 species, which does not produce the same dog tape-worm, as 

 several writers suppose. Young lambs are more liable to be 

 infected by this parasite than sheep, the liability decreasing 

 with age. This parasite is by no means uncommon, and is 

 always abundant in proportion to the number of dogs in any 

 country. Thus, in Iceland, where both dogs and sheep are 

 kept in large numbers, Dr. Krabbe found this tape-worm in 

 eighteen per cent, of the dogs, while the two other tape-worms 

 dangerous to sheep were found even in much greater num- 

 bers. "Giddy" sheep are, of course, very abundant in that 

 unfortunate country. In this country the disease is far more 

 common than most persons suppose. 



That this disease is caused in the manner described above, 

 has been repeatedly proved by direct experiments made by a 

 number of naturalists. The following by Dr. Kiichenmeister, 

 was one of the earliest : " On the 6th of January, 1854, at 8 

 o'clock in the evening, and on the 7th of January, at 11 o'clock 

 in the forenoon, I gave some mature proglottides (joints) of the 

 Tcenia coenurus of the dog to six lambs of from six to nine 

 months old, taken from three different flocks, which were not 

 subject to vertigo. On the 20th of January the animals exhibit- 

 ed the first symptoms of vertigo. They were then successive- 

 ly killed, and presented the following phenomena on exami- 

 nation. 



On the seventeenth day after the introduction, from twenty 

 to thirty vesicles (Coenuri) inhabited the surface of the brain ; 

 the substance of the brain was hollowed into galleries as though 

 a Sarcoptes had been formingits passages (see Figure 65) ; the 

 vesicles were still free and without envelopes, and of the size 

 of a grain of millet. 



On the twenty-fifth day the vesicles were larger. On the 

 twenty-sixth day they were of the size of a lentil ; the envel- 

 opes began to be formed, and the first traces of heads appear- 

 ed. On the thirtieth day, the heads, under the form of tuber- 



