Altgvst 12, 1904. 



SCIENCE. 



209 



low elevation, certainly as low as 3,000 feet. 

 A few scattering trees are found on the 

 banfe of Swan River near the laboratory, 

 while forests of this species may be seen at 

 the upper end of Swan Lake. Here the 

 trees are large enough for logging. A tree 

 at 3,000 feet elevation aged 120 years was 

 one third larger in diameter than one aged 

 200 years at 7,500 feet. The age of the 

 largest trees at elevations about 7,500 feet 

 is about 200 years. 



The alpine pine, Pinus albicaulis En- 

 gelm., takes the place on the higher slopes 

 of the yellow pine, Pinus ponderosa Laws., 

 on the lower levels. The yellow pine is the 

 pioneer, pushing out into the dry and un- 

 occupied valleys, preparing the way for 

 those species requiring more moisture. The 

 alpine or white-barked pine can not tolerate 

 moisture. It is practically absent in the 

 protected amphitheaters at high elevations, 

 leaving the alpine fir to hold full sway. 

 The alpine pine takes the dry slopes, ex- 

 posed to the sun, or the rocky ridges where 

 soil is scanty and where existence is had 

 by the severest struggle. It prefers a nar- 

 row and storm-swept ridge, or a dry and 

 scorching slope, to the quiet, protected, but 

 damp slope. Its gnarled, twisted and 

 broken trunk is in marked contrast to the 

 tall, tapering and stately alpine pine on 

 the opposite side of a ridge, but a few rods 

 away. 



The lodge-pole pine, Pinus murrayana 

 'Oreg. Com.,' is a follower of other species. 

 After the yellow pine, tamarack, or Doug- 

 las spruce has made a dense forest, making 

 a rich and damp soil, a fire may clear the 

 forest. Then the lodge-pole springs up, as 

 thick as it can stand. The region adja- 

 cent to the laboratory shows this, where 

 tall boles of monster tamaracks or yellow 

 pines, amidst dense masses of younger 

 lodge-poles, tell a mournful tale of magni- 

 ficent forests but recently laid waste. Its 



ability to produce cones in a single year, 

 coupled with the early maturity of the 

 tree, six or seven years, gives the lodge- 

 pole a firm hold on the soil. But it is its 

 own destroyer, since it is intolerant of 

 shade and may be squeezed out again by 

 more hardy rivals. How many successions 

 of species of forest trees there may have 

 been will never be known. The evidence 

 points to three in recent times : Yellow pine 

 —Douglas spruce, tamarack and lodge-pole. 

 Extensive collections have been made of 

 the fresh-water invertebrata of the western 

 end of the state. By means of a canvas 

 boat the soundings of mountain lakes have 

 been made, and the life of the waters gath- 

 ered for future study. These soundings 

 and dredgings have been made during the 

 past five summers, and much material and 

 information has accumulated as the result. 

 Lakes hitherto called bottomless are known 

 definitely. Flathead Lake, covering more 

 than three hundred square miles, has at 

 no place a depth of more than three hun- 

 dred feet. Enough work has been done to 

 prove that at some seasons of the year the 

 entomostraca have a decided diurnal or 

 nocturnal movement, ascending to or 

 toward the surface at night or during 

 cloudy weather, descending when the sun 

 shines. The depth to which they descend 

 is from twenty-five to thirty feet. This 

 corresponds almost exactly to the limit of 

 vision when the white net is lowered into 

 the clear and blue water. Again, for some 

 unknown reason, certain species seek the 

 surface during the hottest weather and 

 brightest sunshine, when they may be dip- 

 ped up with a tin-cup. Daplmia thorata 

 Forbes was exceedingly abundant in 1901, 

 when Forbes made his visit to the region, 

 but at no time in the five years' collecting 

 have we found it in large numbers. There 

 is much room for study of the plankton of 

 the region, and the Avaters at such varying 



