576 SCIENCE PROGRESS 



Dr. Fantham at Cambridge ; but enough has been said to 

 show the nature of the disease, which is well known to occur 

 in several other animals. There is a Coccidiosis of the rabbit 

 and a very fatal form attacks pigeons, fowls and pheasants, 

 and the grouse Coccidium, if administered to chickens, will set 

 up the disease in fowls. 



To repeat a little, for the life-history of this parasite is very 

 complicated : 



The chief source of contamination on the moors is the 

 droppings of other diseased grouse. The droppings contain 

 thousands of cysts (oocysts) or spores of the parasite and 

 these spores, with their hard coats, are extremely resistant 

 and can endure for very long periods without the death of 

 their contents, which gradually divide to form four smaller 

 spores inside. The spores are scattered over the moors by 

 the action of the wind and rain and, alighting on the heather 

 or in the tarns of the moors, are taken up by the grouse in 

 their food or drink. When the cysts are swallowed, they 

 enter the gizzard of the bird and pass unchanged into the 

 first part of the intestine, called the duodenum. Here the 

 pancreatic juice is poured into the intestine, to aid in digestion, 

 and under its influence the cyst-wall is softened and dissolved, 

 and the four small spores (contained within the ripened spore 

 or oocyst) are set at liberty. Each small spore contains two 

 active motile germs or sporozoites, which emerge from the 

 softened spore-case and proceed to penetrate the epithelium 

 of the duodenum. The young parasites ultimately cause the 

 destruction of the lining of the first part of the small intestine 

 — the region where, normally, the most active digestive pro- 

 cesses occur. The Coccidium parasites multiply in the duodenal 

 epithelium and then invade the caeca or " blind-guts," with 

 disastrous results. 



Sooner or later a limit is reached, on the one hand, to the 

 power of the grouse chick to provide nourishment for the 

 parasites, and on the other hand to the multiplicative capacity 

 of the parasites themselves. The Coccidium then begins to 

 reproduce sexually. Many small male parasites are produced, 

 together with larger food-containing female Coccidia. The male 

 and female parasites conjugate and then encyst, bursting through 

 into the cavity of the gut and giving rise to the spores found 

 in the caecal droppings on the moors. 



