MALARIA IN GREECE ROSS. 699 



western extremity of the plain rises the magnificent mass of Mount 

 Parnassus, the Mountain of Apollo, with its summits clad in dazzling 

 snow. But to resume. The Kopaik Plain itself is almost absolutely 

 flat right up to the feet of the hills which bound it, being, indeed, 

 the dried bed of a lake. In ancient days, according to the interesting 

 writings of Dr. J. G. Frazer, of Cambridge, this lake was a large sheet 

 of water in the winter, and in the summer a series of marshes over- 

 grown with sedge, with rivers winding through them and patches of 

 dry land between. The lake was drained in very remote times by 

 the people of Orchomenos, a town upon its banks, and the remains of 

 the drainage works are still visible. The water enters from numbers 

 of small rivers and streams gushing out of the surrounding moun- 

 tains and naturally escapes, singularly enough, into great caverns, of 

 which there are many, called " katavothrse." In the Middle Ages 

 the drainage works appeared to have been allowed to fall out of re- 

 pair, but recently a French company resumed the task, and still 

 more recently the work was taken up by the British company, the 

 Lake Kopais Company, which asked me to study the malaria for 

 them. The whole bed of the ancient lake is now a great plain covered 

 with crops of all kinds, which repay the cost of the engineering 

 works. The water is at present discharged through adjacent valleys 

 into the sea. 



It was here that the malaria was so troublesome. The Lake Kopais 

 Company has many hundreds of employees and tenants, who were 

 constantly being attacked, although most of them were natives of 

 Gre'ece. It had not been found possible to keep accurate statistics 

 of the annual number of cases ; so that my first care was to make an 

 estimate for myself of the amount of malaria present. This can be 

 done with a fair degree of accuracy, without the help of statistics, in 

 two ways — by ascertaining the proportion of people which, first, have 

 the parasites of malaria in their blood, and, secondly, possess enlarged 

 spleens. The first method was much used in India by Stephens and 

 Christophers, who called the ratio of infected persons to the total 

 jjopulation the endemic index. To obtain an absolutely correct figure 

 by this means we must make an exhaustive microscojDical examination 

 of the blood of every person in the area under consideration ; but this 

 would be too laborious for practical purposes; and we must conse- 

 quently content ourselves with an approximate valuation obtained by 

 examining only a part of the local population. As shown by these 

 observers, and by Professor Koch, it is especially the native children 

 in a malarious locality who have the parasites in detectable numbers — 

 the older people becoming comparatively immune. The blood of a 

 number of unselected children is therefore carefully searched for the 

 parasites, and the ratio so obtained is recorded as the approximate 

 endemic index. For exact work a large number of children must be 



