MtO Huriis. Ixegonerat iitn ;in(] ifs i-clutiun to traiimatropism. 



(licuhir. Tlit-y wcic ;ill<i\vcd t(j iviuain in ihis posilion in llie- 

 ciists for poriods ranging from twenty two hours to more than 

 eight days. At tlie end of tliis timc they Avere released and 

 grown in wator or a danip at]n()s])liore. In sixty to eighty mi- 

 nutes tlio roots showed tho trauniatropie cnrve. The reaction 

 was the same as it would liave boen ciglit days before „liad it 

 not been hindered by mechanical means". A])parently the latent 

 period was prolonged in the one case over eight days. 



Two points of view were possible."*) Eitlier the influence of 

 the stimiüiis was conducted to the elongating part of the root 

 and tliere held eiglit days or eise, there was a continual Stimulus. 

 To determine this point the author cut off the wounded area 

 after the root had been in the casts twenty-four hours and re- 

 turned to their casts. They were finally removed from the casts 

 and grown in water in a vertical position. Of eleven roots of 

 Lupinus albus six showed a negative curve but this was not al- 

 ways at right angles to the first wound. Some were oblique. 

 This niethod however is open to criticism in that a second Sti- 

 mulus is introdueed the result of which it is impossible to separate 

 from the result of the first. However this was only a side (piestion 

 to the theme in hand and the author dismisses it with these 

 words,'^) „that the latent period may by such artiücial means be 

 extended to more than a week is a face of sufiicient physiological 

 impoi'tance to Warrant the more extended investigation which it 

 IS li(jped may hereafter be given it". 



It is with this question that the present paper deals. 



Materials and metliods. 



The experiments recorded here were conducted in the winter 

 and sj^ring of 1902 when 1 w^as making a general study of tlie 

 latent period on roots under the direction of Prof. F. C. New- 

 combe. 



The experiments were conducted for the most part on the 

 roots of Vicia Faba and Pismii sativum. 



The wounding was done with a glass rod or by cutting. The 

 tirst method was the one generally used. The glass rod was drawn 

 to a fine tip which w^as heated to redness and then brought in 

 contact with the growing root-tip one to one and one-half mm 

 from the tip. A few minutes after burning a small brown sjjot 

 could be Seen which indicated the amount of tissue destroyed. 



After wounding the plants were placed first, under condi- 

 tions stopping both growth and curvature; second, others under 

 conditions stopping curvatm^e only; and still others under condi- 

 tions allowing both. 



In every case control plants were used and an effort was 

 made to work only with strong growdng plants. The results cited 

 were obtained from work on a large number of roots but only a 

 few will be noted in this paper. 



