304 IOWA STUDIES IN NATURAL HISTORY 
chief industries. Butter, cheese, and other milk products from 
this valley form a goodly part of the six million pounds’ worth 
annually exported from the Dominion. Milking is largely done 
by machinery and the products are collected in large lorries daily. 
At Hamilton there is an extensive Agricultural Experiment Sta- 
tion which compares favorably with those in the States. The 
divide between the Waikato and Thames is in places a low in- 
tractable peaty marsh overgrown with ti trees. The higher land 
is being cleared of native timber for grazing. Here and there the 
Australian gum trees have become established in place of the short 
tree-ferns and rimu, while many clearings are overrun by the 
Scotch igorse, a thrifty yellow-flowered shrub, which makes im- 
penetrable thickets. This fast-growing invader is becoming a 
pest. It is said that the first bushes brought from the mother 
country were planted with religious ceremony by the homesick 
settlers! The lava plateau is reached at Mamaku although con- 
siderable voleanic ash is apparent in railroad cuttings on the way 
up. 
Rotorua is situated on the shore of a lake of the same name in 
the midst of a region filled with hot springs, fumaroles, boiling 
mud pools, and small geysers. The air is noticeably charged with 
hydrogen sulphide; one’s watch case turns black, and even coins 
in one’s pocket lose their luster. Some of the thermal springs are 
particularly rich in minerals, and well-equipped, curative baths 
are extensively patronized by those seeking relief from various 
ills. The sanitarium and spa buildings are attractive and well 
constructed. The Maori villagers of Ohinemutu on the shore of 
the lake cook their food and wash their clothes over natural steam 
holes. In a little cemetery near by a vigorous hissing steam vent 
issues out of a tile set between two graves. It is hoped that the 
situation casts no reflection on the departed. King George V Hos- 
pital is situated on a ridge near by. It was here that many con- 
valescent soldiers were so beneficially treated by the hot mineral 
waters during the late war. 
Whakarewarewa, or just Whaka for short, is the site of an old 
erater basin about a mile out of the city. This area is filled with 
hot pools, hissing steam vents, and boiling mud pots. This was 
the home of a very vigorous geyser, Waikite, which became in- 
active twenty years ago except for one dying eruption a few 
months previous to our visit. Its terraced cone of grayish white 
