INFLUENCE OF RADIO-ACTIVITY 347 



the cellular constituents, and the younger or more highly specialised 

 a cell, the greater is its molecular instability in a general sense. 

 There is also, further, the action of decaying emanations, which 

 causes hypereemia of the exposed parts, but it must be remembered 

 that the emanations are gaseous and can therefore reach directly 

 the more remote parts of a respiratory apparatus, which can only be 

 reached by radio-activity itself through the body walls, which 

 have naturally an inhibitory effect. Again, it is a general truth 

 that the physiological effects of all irradiations occur where they are 

 absorbed, and in consequence the coefficient of absorption of the 

 different tissues for each form of radio-activity must be remem- 

 bered. 



The proofs of these generalisations are abundant. Danysz 

 found that excessive radio-activity caused convulsions, paralysis 

 and death in 10 days of a mouse, and the effect was due to 

 7 rays, and penetrating ft activity. Bacilli anthracis were destroyed 

 in 2-4 hours. A. B. Green found that the radio-activity of 10 mgs. 

 of pure Ra Bromide killed B.C.C. and the spirillum of cholera in six 

 hours. He also found that the micro-organisms killed by irradiation 

 give rise themselves to ft activity. Dorn, Baumann and Valentiner, 

 experimenting with 30 mgs. of Ra Bromide, found that all germs 

 submitted to the radio activity were at first arrested in their growth, 

 and finally killed in periods, varying up to ten days. 



Zuelzer found in all cases that excessive radio-activity caused 

 death : Pelomyxa was killed in from 10 minutes to 4 hours, 

 amboebae in 3 to 4 hours. Shelled organisms {e.g., difffugia and 

 arcella) were shown to be more resistant ; after 10 minutes' exposure 

 to radio-activity their pseudopodia were withdrawn, and they 

 dropped to the bottom of the vessel ; after continuing the exposure 

 for three days they were placed in a fresh culture, and in two hours 

 their vitality was completely restored. He found that in small 

 doses radio-activity was a stimulant, in large doses a destroyer. 

 These results have been confirmed by Dreyer, Wilcock and Salmon- 

 sen amongst others. 



Bohn, experimenting on the larvas of frogs and Bufo vulgaris, 

 found that development was retarded and pathological monsters 

 were created, many of which died. The characteristic feature of 

 these monsters was that the dermis was very much affected and 

 contorted. This latter is an important point. Perthes obtained 

 similar results by experimenting on Ascaris megalocephala, and 

 Schafer on Rana esculenta. 



In the plant kingdom very similar results have been obtained. 

 Gager's most important results are summarised : — 



" The early stages of seed germination are accelerated, if stimulation 

 ranges between the minimum and optimum points, otherwise they are 

 retarded. Seeds are less sensitive to the rays, when drv' than when soaked 

 When seeds are stimulated during germination, subsequent growth is re- 

 tarded ; but radium rays, acting through soil in which plants are growing, 

 accelerate both germination and subsequent growth of the shoot. The 

 growth of plants is retarded in an atmosphere of decaying radium emana- 

 tions." 



