102 EVOLUTION 



those ugly^ chapters of natural history which 

 follow tKg (^feyjjne ftf _ SQ many jorois of life, 

 even high an^ heai^'fiil ppes. jnto deggnera.- 

 tiong ^Hl-m'g'h irfprPrliKI^ infck.. 



even Ipftth^nnifti For one thing, even the 

 most thoroughgoing creationist and Paleyan 

 of old must have had some qualms in ascrib- 

 ing the intricacies of parasitism to special 

 creation, or its pains and enfeeblement, so 

 varied and so widespread among all the 

 higher animals, to beneficent design; thus 

 the evolutionary parasitologist has had it 

 practically all his own way, yet has also 

 cured us, with his gruesome lists of pestif- 

 erous creatures and lurking dangers, of that 

 dream of this as the best of all possible worlds 

 to which a too facile evolutionism has been 

 wont to incline. Sp<yupg-of a,]] TrprmAi^nf 



prniips, he sTiowp i^g 1 Tna.y fall jnto pa.ra.si- 

 tisnk the simplest bacteria and lower fungi, 

 the more active and long supposed innocent 

 Protozoa above all so that for a generation 

 past the vast field of pathology has seemed 

 well-nigh divided between bacteriologist and 

 parasitologist proper. Ibis amQpg the Vgr- 

 teJarates, which., only, faj^into parasitism^yi 

 the Tfljgst gg.sfg5=f. thflt \nfestation_ is ^jnost. 

 frequent. Fishes may even swarm exter- 

 nally with trematodes and parasitic crus- 

 taceans, internally with cysts and intestinal 



