218 BEPORTS ON THE STATE OP SCIENCE. — 1915. 



in this species has been reported on (Cameron and Vincent, J. Med. 

 Res., May 1915), which is the first observed in salt-water fislies. The 

 thyroid of the rat-fish {Hydrolagus collicii, a holocephaloid) contains 

 quantities of iodine varying from 0"5 to 0'75 per cent, (different 

 samples). Several species of sea-birds have been examined. The 

 thyroids of the surf scoter (2 specimens) contain 1"1 per cent., of the 

 pigeon guillemot 0'4 per cent., and of the marble murrelet 0'3 per cent. 

 The thyroids of crows {Corvus corvinus), feeding largely on clams, 

 contain 0'75 per cent, iodine. These are all high values. The 

 increasing ratio, previously shown to exist between the weight of the 

 dried thyroid and the weight of the animal, with increased development, 

 is confirmed. For Squalus sucklii it is about 6 mg. per kg., for 

 Hydrolagus collicii about 12 mg. per kg., and for the birds examined 

 the average figure is 25 mg. per kg. 



The Committee ask to be reappointed with a grant of 35Z. 



Electromotive Phenomena in Plants. — Report of the Committee, 

 consisting of Dr. A. D. Wallee (Chairman) , Mrs. Waller 

 (Secretary), Professors J. B. Farmer, T. Johnson, and 

 Veley, and Dr. F. O'B. Ellison. 



The Electrical Measurement of the Vitality of Vegetable Tissues. 



Plumule V. Radicle. 



By A. D. Wallee, M.D., F.R.S., and A. M. Waller. 

 In pursuance of experiments described in a previous Report to the 

 Association (Birmingham, 1913, p. 241) we have endeavoured to, 

 estimate the relative vitality of the stems and roots of seedlings by 

 measuring the voltage of the blaze-currents excited by single induction 

 shocks.* We took for this purpose the seedlings of barley — Hordeum 

 vulgare — applying the test to the separated plumule and radicle 

 respectively on the fourth and on the sixth day of germination on 

 moist blotting-paper at a temperature of 18° to 20°C. As in pi'evious 

 experiments, we used two galvanometers in circuit in order to read upon 

 one or other of their two scales values of first responses, whether these 

 happened to be of low or high voltage, but we give our results reduced 

 to one of the two scales, that, namely, in which 001 volt through 

 I'lO' ohms give a deflection of 12 degrees. The distance between the 

 unpolarisable electrodes upon which the plant is laid was kept as nearly 

 as possible constant as 5 mm. The galvanometer connections (see 

 fig. 1) were taken such that the injury-current in the plant from the 

 cut end B to the tip A was positive, so that the first response to an 

 induction shock in the same or in the opposite direction was directed 

 from A to B (in the plant), i.e., in the negative direction. [We observe 



* The Report in question is itself a continuation of work first described 

 in 1900. Waller, ' An Attempt to Estimate the Vitality of Seeds by an' 

 Electrical Method,' Proc. Boy. Soc., vol. 68, p. 79, 1901. Also Waller, ' Signs 

 of Life from their Electrical Aspect,' John Murray, London, 1903. 



