92 TJiirfif-First Aniiiuil Meetiug 



not allowcil to root in the soil, and are limited to the bdce water 

 for nourishment, an ahnoriual growth results, which is mani- 

 fested hv diminished volume of vegetation and total dry weight; 

 also, 1)\' an excess of starch, and deficiency of nitrogen, potash 

 and phosphoric acid. 



Considering now the question, are the roots merely organs of 

 attachmeiit, or are they also for the purpose of ahsorption? It 

 is not a difficult nuitter to separate the roots of a plant from the 

 stem, so that solutions differing in chemical composition, may 

 be ofl'ered to each at the same time. In this way lithium nitrate 

 may be offered to the roots, so that the lithium, if found later 

 by spectroscopic examination in the upper parts of the plant, 

 may be positively known to have been alosorbed by the roots 

 and conducted upward into the stem. It is also possible to con- 

 struct an apparatus by which the amount of water absorbed by 

 a root in a given time can be measured. Both of these methods 

 have been employed, and there can l)e no doul^t l^ut that the 

 roots are organs of absorption. ]\Ioreover, the roots of most of 

 our common aquatics develop structures, the presence of which 

 is almost prihia facie evidence that the organs bearing them are 

 for absorption. These structures are the so-called root hairs, 

 and they occur on all of our terrestrial plants, with a few excep- 

 tions. Examination has now shown that they are common also 

 on the roots of aquatic plants. These hairs are simply ordinary 

 root cells which are protected from the outer cell layer of the 

 root, for the purpose of securing the maximum absorbing sur- 

 face with the least expenditure of tissue. 



We may next enquire, what quality of soil is best suited to 

 supjiort a good plant growth? Last summer here at the Hatch- 

 ery, three soils were tested. One Avas a loam from 8quaw harbor 

 like ordinary garden soil, another was sandy Avith plant remains 

 scattered through it, and the third was clayey. The same species 

 was grown at the same time in each soil under otherwise mitnral 

 conditions. The ])oorest growth occurred on the clay, the second 

 best on the sandy soil, and the best on the loam. Thus is con- 

 firmed experimentally the observation made from the study of 

 all the plant beds in the region of these islands, that other con- 

 ditions being favorable, the most abundant growth of aquatic 

 plants occurs on what would he called a good truck soil. ^lany 



