G. GENERAL NATURAL HISTORY AND ZOOLOGY. 295 



BLOOD EXTOZOON. 



A blood entozoon has lately been described by Dr. T. R. 

 Lewis as occurring in a patient suffering from a tropical dis- 

 ease called cliyluria. The worms appear to be present in 

 very large numbers in the blood, and in some of the secre- 

 tions ; indeed, they were first observed in the urine. Noth- 

 ing, so far, is known of their manner of development, nor how 

 they gain entrance to the body. Their average length is 

 0.0175 of an inch, and they are therefore much smaller than 

 the Trichina sinralis. 12 A^ February 13, 1872, 289. 



KELATIOX OF EXTOZOA TO THE GROUSE DISEASE. 



English sportsmen are greatly exercised over the preva- 

 lence of a disease among the grouse in the Highlands, which 

 even threatens their extermination, or, at least, a very seri- 

 ous diminution of the numbers and strenotli of that noble 

 game bird. This is in every* respect different from the dis- 

 eases that have heretofore prevailed on the moors, as the birds 

 are in perfect plumage, but wasted to skeletons, with large 

 quantities of undigested berries in their crojDS. In the sea- 

 sons of 1847, 1856, and 1865, the infected grouse exhibited a 

 dull disordered plumage and attenuated bodies. In 1867 

 they were in good plumage and healthy in appearance, per- 

 fectly plump, although the liver was discolored and soft. 



The precise nature of the disease has not yet been estab- 

 lished, although Dr. Macdonald is of the opinion that it may 

 be due to the ravages of entozoa, or intestinal worms. An- 

 other correspondent o^ Land and Waaler is inclined to assign 

 as the cause the insufficient supply of young and tender shoots 

 of heather for the bird's food, since the rank and decayed 

 fibres, old seeds, and berries, lack the nutrition necessary for 

 the healthy condition of the grouse, and to the want of a suit- 

 able cover for their protection in winter. Another very im- 

 portant difficulty, in his opinion, is the overstocking of the 

 moors, and the overtrapping of birds of prey, and of so-called 

 vermin. Quite a number of naturalists have given this as 

 the probable cause of the deterioration of these birds, since 

 it is a well-known law of nature that the weak and sickly 

 first fall a prey to the attacks of their enemies, those that 

 escape requiring that great degree of vigor of flight which is 



