WALDRON— THE PEANUT 325 



the root tip tissue here is more active and vitalized than later, and 

 so is more sensitive to external stimuli. It was noted that when tip 

 hairs were produced usually no rosettes were present. Possibly 

 these offset the need for tip hairs, or at least utilize energy which is 

 lacking for their later formation. 



Absorption 



From the foregong observations on the roots and root hairs of 

 the peanut, it is evident that the young plant absorbs its water and 

 mineral foods by any one, two, or all of the following means, depend- 

 ing on environment and growth conditions: (i) Through the epi- 

 dermis of young roots the thin cuticle of which is mucilaginized; (2) 

 By means of normal tip hairs on vigorous growing roots; (3) By 

 means of the rosetted, basal hairs. The first and last are undoubtedly 

 the most important of these. As soon as the fruit stalks appear and 

 reach the soil, hairs are at once formed from the epidermal cells of 

 these. The older plants then have a much more extensive absorbing 

 surface from the formation of a considerable number ot gynophores. 



Proof that these hairs do supply water to the plant is indicated 

 by the fact that, according to Pettit, when the roots of such are 

 severed the plant continues active and apparently uninjured for 

 some time. The xylem of the gynophore bundles, although not very 

 large, is sufficient to carry a considerable quantity of material. The 

 nearly mature fruit must also absorb some water as indicated by 

 the presence of delicate absorbing hairs. How important this is it 

 is difficult to say. That they are not absolutely essential is evident 

 from the fact that the fruit continues to swell somewhat if trans- 

 ferred from the soil to the air, causing the hairs to dry up. The 

 absorbing fruit stalk undoubtedly takes the place of roots to a cer- 

 tain extent. Root tubercles, which also appear at about the same 

 time, should be noted too in this relation, since some other nodule- 

 producing members of the Leguminosae, as is well known, seem to 

 have a reduction of root hairs. The absorbing surface of roots alone 

 on these older plants is comparatively small. 



Development 



Germination. The writer, in attempting to raise plants for study 

 in the greenhouse, had some difficulty in keeping insects and mice 

 away. Some of these seemed to have no difficulty in locating the 

 seed even before germination. A wire cage was finally built which 



