330 WALDRON— THE PEANUT 



for about a month. They usually attained five or six inches in 

 length and then wilted just back of the ovary. The longest gyno- 

 phore produced in this way was seven and one half inches in length 

 — nearly twice as long as any seen by the writer in the soil. Hairs 

 developed which gradually died away until there were but a few near 

 the tip. Other gynophores were allowed to grow in test tubes of 

 tap water, some kept in the dark, others in the light. These pro- 

 duced no hairs. Two of those in darkness, after eight weeks, pro- 

 duced a small one seeded fruit. The remainder produced none. 

 Others were allowed to grow into sphagnum and pure sand and re- 

 sulted in fruit formation in both cases. Gynophores which had pen- 

 etrated soil and whose ovary had begun to swell were exposed to a 

 saturated atmosphere and to ordinary greenhouse conditions. In 

 the former case, the fruit turned green and continued to grow 

 slightly, while the latter turned green and remained small. 



The results of these trials, although not at all conclusive as to 

 evidence offered, indicate that (i) a thigmotropic, hydrotropic or ap- 

 oheliotropic stimulus, or a combination of these, is necessary for the 

 ovary to begin maturation, but (2) that a continuation of such is 

 not necessary, since the ovary continues to develop somewhat if 

 removed from the soil after its growth has begun. This develop- 

 ment, however, is somewhat abnormal. All successful experiments 

 were produced in complete or partial darkness, although those 

 in the moist dark chambers failed. This suggests the necessity 

 of the first two factors, i. e., water and contact. More research is 

 necessary in order to clinch this point and determine which of the 

 three is the most important. 



From the writer's observations and from the varying results of 

 the above attempts at fruit production, he feels that two things 

 should be kept in mind — (i) the condition and activity of plant 

 growth, (2) the ability of the plant to possibly supply the necessary 

 substances to the fruit in two ways — (a) by direct absorption of 

 some of them from the soil with the carbohydrate supply from the 

 plant; (b) by transfer of all necessary materials from the vegetative 

 organs into the fruit. A number of plants that became pot-bound, 

 when several gynophores were being formed on them produced only 

 one or two small fruits. Similar plants that had abundant pot- 

 room produced several. Weak plants may have been experimented 

 with. In the field, many poor fruits without seeds called "pops" 

 are found — due possibly in part to this same cause. 



