6 NEUTRON EFFECTS ON ANIMALS 



The cell protoplasm is toward the acid side, surrounded by a boundary 

 or membrane; the cell nucleus is alkaline; the environment, the blood 

 plasma, is slightly alkaline. These changes in acid-base equilibrium (pH) 

 may seem small to the chemist, but they loom large to the student of vital 

 systems where small changes in pH are of great importance, for upon that 

 as one of the factors depends the continuance of the vital equilibrium or 

 balance, the milieu interne of Claude Bernard. 



Thus, in attempting to explain the action of neutrons upon vital systems, 

 one question must be answered. In what part of the vital system does 

 the effect take place? Is it on the nucleus, the protoplasm, the cell mem- 

 brane or the environment? If that can be answered the area of research 

 is lessened. In the action of short ultraviolet light, the effect is apparently 

 upon the nucleus. In X-rays' effects, there is no full proof, but it is sig- 

 nificant that the effect of X-rays is greater upon those cells having greater 

 amount of cell nuclear elements. This is shown particularly in growing, 

 immature tissue and in certain cancers which are spoken of as "radio- 

 sensitive" in that they are more easily affected by X-rays, and have, as a 

 rule, a larger amount of nuclear tissue containing more nucleic acid than 

 normal. Apart from this, there is little evidence as to the site of X-ray 

 effect. 



The most significant fact in neutron bombardment is its effect upon 

 growing or immature tissue : this tissue has the largest amount of nuclear 

 elements. This is most marked in the testes, the lymph tissue and the 

 white blood corpuscles. The latter may be considered extremely young 

 tissues, for in man they are renewed at least every twenty-four hours. 

 The normal white blood corpuscle count of man is from 5,000 to 8,000 

 white cells per cubic millimeter. If the amount of blood in a man of 145 

 povmds is taken as 6 liters, then 30 billion white blood corpuscles are re- 

 newed every day. This seems incredible, yet many things connected 

 with the human body seem incredible. 



The number of lymphocytes present in the circulating blood of the cat 

 has been estimated by Sanders, Florey and Barnes (3) at 1250 million. 

 This number, they calculated, was replaced from one-half to almost 3 times 

 every twenty-four hours. For rabbits the daily output of lymphocytes by 

 the thoracic duct was 4 X 10^ and the lymphocyte population was replaced 

 with fresh cells about five times daily. The white blood corpuscles have 

 such a short life and are so frequently renewed that they must be con- 

 sidered extremely young, fragile and immature tissues. They must also 

 be present, owing to their short life and quick replacement, in all stages of 

 very rapid growth and development, since their total life is not more than 

 twenty-four hours. They are truly impermanent and ephemeral. 



The source of the white blood corpuscles is believed to be in the bone 



