240 THE GROUSE IN HEALTH AND IN DISEASE 



cell like the segments of an orange or the staves of a barrel (PI. xxxiv., 

 Figs. 20-22 ; PI. xxxv., Figs. 23, 24). Owing to this method of grouping, the 

 merozoites are said to be arranged " en barillet." The groups, when ripe, soon 

 break up, and the individual merozoites are liberated. The movements of the 

 merozoites, w^hen free, resemble those of the sporozoites. 



The number of merozoites formed from a single schizont seems to vary. Eight 

 to fourteen seem to be common numbers, but as many as twenty have been found. 



The merozoites finally are slightly curved vermicules (PI. xxxv., Figs. 23, 24), 

 possessing a nucleus wJiich may be approximately central (PI. xxxiv.. Figs. 20, 21) 

 or somewhat towards one end (PI. xxxiv.. Fig. 22 ; PI. xxxv., Fig. 23). The 

 nucleus of the merozoite is small, and the presence of a karyosome is often not 

 very evident, though there is a small granule of chromatin — representing the 

 karyosome — usually to one side of the nucleus (Fig. 24). The ends of the 

 merozoites are rather less pointed than those of the sporozoites, a feature that E. 

 avium has in common with E. schubergi as described by Schaudinn. 



When the merozoites reach a new host-cell, they enter, become round, and 

 proceed to grow as trophozoites in the same way as did their parent organism, and 

 vxndergo later nuclear fragmentation in a similar manner. As the result of this, 

 many more merozoites are produced, and as schizogony may be continued through 

 several generations, the destruction of the gut-epithelium is very extensive 

 (PI. XXXIV., Fig. 1). 



Towards the end of schizogony — especially in the csecum — relatively smaller 

 schizonts with larger and fewer merozoites (Fig. 25), about five in number on the 

 average, are produced. These larger merozoites appear to be formed near the end 

 of infection, in company with large numbers of gametocytes, so far as evidence is 

 available. 



These difi"erences in the schizonts might be taken by some investigators to be 

 indicative of difierence in species — in other words, that more than one species of 

 Coccidium may occur in the gut of Grouse. I do not state that this is not so, but 

 personally prefer the view that the di3"erences in the schizonts and merozoites 

 noted are refiexes of the condition of nutriment of the parasite. Wenyon (1907) 

 has some interesting observations on the variations in the schizogony of E. 

 falciformis in the mouse, and states that the variations are due to the nourish- 

 ment available for the parasite. Again, the species found in the liver and gut 

 of the rabbit (Coccidium oviforme and C. j^^^'Jorans) are now usually united 

 into one species, Eimeria stiedce. 



