436 



Miss J. White. TJie Ferments and [Mar. 3, 



From the third column on the list it can be seen that, on the whole, 

 though not without exception, the resistances to extreme cold and to extreme 

 desiccation are approximately parallel. 



4. The Respiratory Activity of Resting Seeds. 



In this series of experiments the respiration of certain other characteristic 

 kinds of seeds was tested in addition to the foregoing cereals. 



"Whether dried seeds respire at all, and if they do to what extent, is one 

 of the most discussed problems in plant physiology, especially in connection 

 with the views as to whether the life in resting seeds is merely at a low ebb 

 or is entirely suppressed. 



The apparatus employed was Aubert's improved form of that of Bonnier 

 and Mangin, and, as was stated in a previous paper dealing with the 

 respiration of gynsecia,* the machine gave complete satisfaction, provided 

 that certain precautions were taken. Before each set of experiments the 

 mercury was removed from the apparatus and was thoroughly cleansed by 

 several washings in strong hydrochloric acid, followed by several washings 

 in distilled water, and then being passed through a filter to dry. 



This precaution was found to be of extreme importance, for in the presence 

 of any impurities such as zinc in the mercury, the inlet of a sample of air 

 into the tube produced oxidation of the zinc, and a consequent diminution 

 of the volume of the sample of air when allowed to stand in the apparatus 

 for a short time. 



The NaOH used was a 40-per-cent. solution, and the pyrogallic acid was a 

 saturated solution diluted to one-fourth its original strength. 



The seeds employed were the ordinary cereals, and also Eucalyptus globulus, 

 Acacia melanoxylon, Cytisus laburnum, Setaria italica, Ricinus cambogiensis, 

 Cannabis sativa, and Pinus insignis — and the experiments were performed in 

 four series. 



1. The seeds used were tested as received from storage. 



2. The seeds before being tested for their respiratory activity were dried 

 in the oven for eight days at a constant temperature of 45° C. 



3. Samples of the seeds after drying for eight days at 45° C. were further 

 heated in the oven for three days. During the daytime the temperature 

 of the oven was 100° C, whilst at night the temperature fell to about 70° C. 



4. Some of the above seeds were still further heated to about 130° C, 

 when all were killed, and the gaseous exchanges were again tested. 



For each respiratory test a weighed quantity of each seed was passed up 



* 'Annals of Botany,' 1908. 



