GANYMEDES ANASPIDIS (nOV. GEN., NOV. SP.). 161 



in the dozen or so of hosts that I examined. The time of 

 year seems to have no effect on any of the processes of the 

 parasites' life. 



As regards the effects produced by Ganymede s, no incon- 

 venience seems to be suffered by the organism of the host as 

 a whole, and only trifling damage is done to individual 

 tissues. Those few cells of the gut epithelium to which the 

 Gregarines attach themselves look generally unhealthy, and 

 their nucleus becomes liyperchromatic (fig. 10) ; and the walls 

 of the liver tubes get more or less distorted by the growth of 

 the large couples in the second trophic phase : but in neither 

 of these ways can any serious harm be done. 



After these preliminary remarks, we may now proceed to 

 consider in detail the structure of Ganymedes in its various 

 stages. 



Detailed Account. 

 (i) The First Trophic Period. 



Although the size of the smallest free Gregarines seen was 

 only 80 — 100 ju, yet I could find no points of difference 

 between them and the adults, save that in the young forms 

 the bodv has not attained to its full size relative to the 

 structures (soon to be described) situated at the extremities. 

 From these small forms all stages may be seen to Gregarines 

 400 — 425 ju long, and 23 — 30 ju broad, though the average 

 size is 250— 300 /x x 17—20^. 



The shape of the body is cylindrical, tapering slightly 

 towards one end, and considerably towards the other. The 

 thinner end is almost certainly anterior in progression, and 

 when attachment takes place, it is by means of a structure at 

 this extremity. This structure in favourable specimens is seen 

 to consist of a sphere connected by a thinner neck to the 

 main body: I propose to call it the ball, and the thin 

 extremity on which it is placed, the ball end. The other 

 end may be called the cup end, for here many individuals 

 possess a perfectly regular hemispherical depression, whose 



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