THE INFLUENCE OF GRAVITY 



81 



nally. Immediately after the stems were split marks were made 

 with India ink on the cortex at a distance of 1 centimeter from 

 each other and then the stems were suspended horizontally, 

 one-half of the split stems having their cortex below, the others 

 having their cortex above. Stems with an apical leaf were used 

 for the purpose (Figs. 60 and 61). Only when the cortex was 

 below did the stems bend (Fig. 60). After 10 days, when the 

 halves with the cortex below had bent strongly, the displace- 

 ment of the marks was ascertained. It was found that the 

 marks on the halves in which the cortex was above (Fig. 61) 

 and which had not bent were practically unchanged (Table 

 XVIII) . The same was true of the marks in the non-bent regions 

 of the other halves, where the cortex was below ; while a growth of 

 15 to 20 per cent of the original length had taken place in the 



Table XVIII. 



-Length of Four Split Stems Placed Horizontally 

 WITH Cortex Above (in Centimeters) 



bent convex region of those stems having their cortex below. 

 Table XIX gives the measurements of four bent stems. 



Table XIX. 



-Length of Split Stems Placed Horizontally with 

 Cortex Below 



Region of stem 

 measured 



Set I 



Set II 



Set III 



Set IV 



Begin- 

 ning 

 of 

 experi- 

 ment, 

 centi- 

 meters 



End 

 of 

 experi- 

 ment, 

 centi- 

 meters 



Begin- 

 ning 

 of 

 experi- 

 ment, 

 centi- 

 meters 



End 



of 

 experi- 

 ment, 

 centi- 

 meters 



Begin- 

 ning 

 of 

 experi- 

 ment, 

 centi- 

 meters 



End 

 of 

 experi- 

 ment, 

 centi- 

 meters 



Begin- 

 ning 

 of 

 experi- 

 ment, 

 centi- 

 meters 



End 



of 

 experi- 

 ment, 

 centi- 

 meters 



A: non-bent apical 

 part 



B: bent central part. 



C : non-bent basal 

 part 



3.2 

 4.9 



2.0 



4.10 

 4.85 



4.15 



