230 BULLETIN UNIVERSITY OF MONTANA 



Daphnia Pond. 



A STUDY IN ENVIRONMENT. 



Morton John Elrod. 



Daphnia Pond lies along the road about a mile and a half south of the 

 laboratory. It is a small land locked pond, covering some 10 or 12 acres. 

 It is undoubtedly of glacial origin, lying in a small pocket between two 

 ridges of rock made by faulting. Its outlet in spring is to Flathead lake, 

 a hundred feet lower in altitude. The pond lies in a glaciated region 

 and is no doubt the I'esult of glacial action. Within a few miles of 

 Daphnia a dozen other ponds of similar nature may be found with similar 

 origin, and offering the same field for study. 



The pond is shallow at either end and 20 feet deep in the middle. The 

 shallow places are overgrown with rushes, moss, water lilies, and other 

 aquatic forms of vegetable life. A small place in the center has open free 

 -water. Around the banks there is the usual growth of willows, while 

 numerous logs and dead bushes make the water difficult to reach. The 

 bottom is largely of boulders, filled in between with mud, and overgrown 

 with rank and dense vegetation. 



The name Daphnia was given because of the great numbers of the 

 entomostracan Daphnia pulex found in the pond. 



Environment is a biological term having reference to the physical 

 conditions affecting an organism. As referred to human beings we say 

 the environment is good when the conditions are so favorable as to lead 

 to good results. When a boy is sent to college he is in a good environ- 

 ment if his professors, his associates, his boarding house, and his com- 

 panions all encouarge him to such effort as will bring about the best re- 

 sults mentally, morally, and physically. 



The environment may, of course, be bad. In that case the results 

 are not what are desired. Bad companions and associates, bad tenden- 

 cies, may bi'ing about conditions of mind and body disastrous to the in- 

 dividual possessing them. 



According to the best information we now possess, when an organism 

 comes into existence it has certain hereditary tendencies. These are 

 only tendencies, and are immediately intensified or diminished by the 

 conditions in which it is placed. In addition to these hereditary ten- 

 dencies each living organism has within itself, be they few or many, some 

 characters which are called acquired characters, which originate within 

 the organism, and are affected the same as hereditary characters. Often 

 these are powerfully influenced by environment, are intensified to a 

 marked degree, and apparently modify the entire life of the species and 

 its descendants. Hereditary or acquired characters or tendencies, 

 affected by environment, make the species what they are. 



