151 



On the POWEE of WITHSTANDING DESSICATION 

 in PLANTS. 



By Alfeed J. Ewaet, D.Sc, Ph.D., 



1851 EXHIBITION SCHOLAR. 



[Read 12th February, 1897.] 



The statement that many seeds and spores as well as 

 certain Mosses are able to withstand complete dessication 

 without their vitality being destroyed is one which is 

 frequently found in text books but which is nevertheless 

 quite erroneous. In no case can anything of a vital 

 nature, in whatever condition or however resistant it may 

 be, be deprived of all water without, at the same time, 

 destroying its vitality. Thus Schroder* has shown that 

 seeds of Hordeum and Triticum, after being kept for 12 

 weeks over H 2 S0 4 in a dessicator, were nearly all still 

 capable of germination but contained, though apparently 

 quite dessicated, from 1 to 2% by weight of water. 

 Similarly with a Jjichen Sticta pulmonariawhich withstood 

 17 weeks dessication over sulphuric acid the minimal 

 " Feuchtigkeitsgehalt " consistent with the preservation 

 of vitality was found to be 5% by weight of water. 



In order to investigate more closely the relation between 

 these two factors a series of experiments, the results of 

 which are given below, were made. The plants or seeds 

 are dried for long periods of time exposed to air or in a 

 dessicator and then, after ascertaining how the vitality of 

 the specimens has been affected by the prolonged drying, 

 a sample is weighed and after heating to 100° C. until no 

 further loss of weight takes place, again weighed. The 



* Schroder, tfber die Austrocknungsfahigkeit der Pflanzen. Bot. 

 Untersuch. aus Tubingen. Bd. II., Hft. 1, 1886, 



