108 NEW ZEALAND PLANTS. 



occupying a low position in the plant-world, their structure is at times 

 fairly complicated, and their methods of reproduction are quite 

 elaborate. To this family belong the diatoms, the stoneworts (Chara, 

 Nitetta), and many others. In the hot springs of the North Island 

 are some peculiar forms, belonging to the blue-green algae, which 

 are able to exist in water of a very high temperature. These were 

 recently studied by Professor Setchell, of the University of California, 

 and in a letter to the author he states that none of the New Zealand 

 forms can endure a temperature greater than 167 Fahr., which seems 

 a bath quite hot enough in all truth ! 



These hot-water algae are sometimes cited to show how living 

 organisms could exist in the early days of the earth when cold water 

 would be unknown, and how such organisms may have persisted 

 since those distant ages, and they or their congeners be the ancestors 

 of our present plant-life. 



RELATIONSHIP BETWEEN LAKES AND MEADOWS. 



Between lakes, swamps, bogs, and meadows there is a close con- 

 nection. Sedges, raupo, rushes, and rush-like plants growing in the 

 shallow water near the margin of a small lake may in time, through 

 their decay, turn that part into dry ground, and advance farther and 

 farther until a water-surface is no longer visible, the whole having 

 become a raupo or phormium swamp. From this, the transition to 

 meadow land is, in many cases, only a matter of time. 



The blocking of watercourses with aquatic plants can soon convert 

 a meadow into a swamp. Even on shingly river-beds, swamps at 

 various stages of growth may be observed, and toetoe grass, palm- 

 lilies, and phormium break the monotony of the scene. 



Sinking of the land may bring about great changes in the plant 

 societies, and remains of plant-life in bogs can teach much as to recent 

 changes in the land-surface. 



In the swamps in the neighbourhood of Christchurch large numbers 

 of fallen trees are found, the remains evidently of a large coastal forest, 

 which must have been replaced by swamp during a sinking of the 

 land. So, too, on that narrow peninsula to the far north of Auck- 

 land is much kauri-gum to be mot with in the bogs, a sure sign that 

 the land stood considerably higher at the time it was occupied by the 

 kauii forest, since that plant is most rare in swamps. 



