994 



SCIENCE 



[N. S. Vol. XXVII. No. 704 



of the organs in action stowed them to be used 

 as intakes for water during inspiration. They 

 are used in this way both while the mouth is 

 so used and also when it is closed tightly. 

 Each of these two internal openings is pro- 

 vided with an independent valve which auto- 

 matically prevents the regurgitation of water. 

 Besides these openings the nasal cavity is 

 also provided with the usual anterior and pos- 

 terior nares. A fuller account of this struc- 

 ture will appear shortly in another journal. 

 TJlrio Dahlgren 



SPECIAL ARTICLES 



BLACKHEAD, A COCCIDIAL DISEASE OF TURKEYS ' 



In many districts of the United States, and 

 in Rhode Island in particular, there has been 

 known to exist since about 1894 a highly in- 

 fectious disease affecting the ceca and liver 

 of turkeys and, to a less extent, of fowls. It 

 is characterized, in the ceca, by inflammation, 

 thickening, occasional perforation of the walls 

 and denudation of the epithelium ; in the liver 

 by enlargement and by the formation of 

 cream-yellow spots. 



Since the investigations of Theobald Smith, 

 published in 1895, it has been commonly be- 

 lieved that the disease is due to an ameba, 

 Amwha meleagridis Smith. The present 

 writers believe they have demonstrated, how- 

 ever, that the disease is caused by a Coccidium, 

 which, according to the nomenclature adopted, 

 may be a variety of Coccidium cuniculi, and 

 that Amoeba meleagridis Smith is probably the 

 sehizont stage in the development of the Coc- 

 cidium,. 



The stages of the Coccidium, most commonly 

 found were the schizonts and the macrogam- 

 etes or' oocytes. The former were first dis- 

 covered in smears by means of a rose-analin- 

 violet and methylene-blue stain. Later they 

 were recognized in fresh preparations, both 

 within and without the epithelial cells. The 

 macrogametes were most common in the cecal 

 and the intestinal content below the junction 

 of the ceca, and were often present when the 

 cyst stage was absent. Besides these stages 



' Abstract of paper read before the Zoologists' 

 meeting at New Haven, December, 1907. 



the microgametocytes, the microgametes, the 

 merozoites and the sporozoites were recognized 

 both in fresh preparations and in sections 

 stained with hematoxylin and eosin. 



By placing the cecal content containing 

 macrogametes in a solution of 10 per cent, 

 potassium bichromate, the growth of bacteria 

 was stopped and the development into cysts 

 and then into sporozoites could be watched. 

 The cysts are commonly oval, and have an 

 average size of 21 by 14 micra. Cultures con- 

 taining cysts were also made to develop in 

 2 per cent, formalin, saturated solution of 

 thymol, 4 per cent, boracic acid, 1 per cent, 

 lysol and 2 per cent, carbolic acid. The 

 organism is common in the soil and is fre- 

 quently found in apparently normal fowls, 

 which do not appear to be so susceptible as 

 turkeys to this form of the disease. 



By means of feeding portions of cecal con- 

 tent or parts of ceca of diseased birds, the 

 disease was produced experimentally in tur- 

 keys, chicks and sparrows, but not in guinea- 

 pigs, kittens or in rabbits. In young turkeys 

 the disease is almost certainly fatal; older 

 birds may recover. It is doubtful if death is 

 caused directly by the Coccidium, in the ma- 

 jority of cases; whether there is a specific ac- 

 companying organism pathogenic to turkeys 

 under these conditions, and less so to chickens, 

 has not yet been determined. In eases of 

 perforation of the cecum, death soon follows 

 from acute peritonitis. No method of treat- 

 ment is at present recognized. 



The investigations reported above were made 

 at the Rhode Island Agricultural Experiment 

 Station, in cooperation with the Bureau of 

 Animal Industry, U. S. Department of Agri- 

 culture, during the year 1906-7. 



Leon J. Cole 

 Philip B. Hadley 



THE NATIONAL CONSERVATION 

 COMMISSION 



Pursuant to the recent Conference of Gov- 

 ernors in the White House on the conservation 

 of our natural resources, the President on 

 June 8 appointed a National Conservation 

 Commission, comprising Senators and Repre- 

 sentatives in Congress, scientific and technical 



