70 



Selby : Studies in etiolation 



The determination of the water and dry matter in the stems of 

 these specimens gave the following results : 



Dry Substance in Stems of Euphorbia corollata 



Normal plant 

 per cent. 



Water.. 86.90 



Dry substance 13.10 



I 

 91. 11 



8.89 



Etiolated plant per cent. 



II Average 



9°-37 



89.63 

 IO.37 



9-63 





Figure A. Normal plant of Euphorbia corollata. 

 Figure B. Etiolated plant of Euphorbia corollata. 



A transverse section of the stems showed (plate 5, figure 1) 

 in the normal a rather feeble development of the strengthening 

 tissue and a cambium of several layers of short cells. The woody 

 parts of the cylinder were irregularly and feebly developed, bring- 

 ing the groups of vessels into great prominence. The etiolated stem, 

 as before stated, showed (plate 5, figure 2) a tendency to develop 

 cortical parenchyma and the woody portion scarcely less devel- 



