758 



After rather more than a week a contrast was noticeable between 

 the green and tlie partially ringed variegated shoots on the one side 

 and the completely ringed variegated siioots on the other. The first 

 two (l**' and 3"' series) continued growing norinallj. The third 

 (2nd series) lagged behind and died otf after 2 or 3 weeks, the 

 leaves having previously shrivelled and dried up. 



Fig. 



That ringing in itself did not injure the plant appeared distinctly 

 from the results of the first and the third series. (See the photos): 

 from left to right we see first 4 completely ringed yellow branches, 

 some brown and dead, others small but still li\ing; the next 

 following are two completely ringed green ones and lastly to the 

 right two partially ringed. The last four have developed normally. 



it is clear that with the completely ringed green shoot the supply 

 of water is normal ; why then does the completely ringed yellow 

 branch die off under symptoms that point to a deficiency of water? 



The reason is obvious. In consequence of too little osmotic pres- 

 sure the absorptive power of the tissues is too low as compared 

 with that of the other parts. 



The researches by Dixon and Atkins ') on the determination of 

 the osmotic pressure by lowering the freezing point of the expressed 



») Notes Botanical School. Trinity College Dublin, 1912. 



