414 PROTOPLASM 



nature is known, they have long since ceased to be enshrouded 

 in mystery. The production of light and electricity by animals 

 might well be questioned by the layman, if not by the scientist, 

 were not both phenomena of common experience. We turn now 

 to a form of radiation from organisms which is not conspicuous 

 and has but recently been discovered. 



In 1923, the Russian histologist Alexander Gurwitsch dis- 

 covered that living cells give off a type of radiant energy which 

 may stimulate other tissues to more active growth. The exist- 

 ence of such energy has been questioned, although it is supported 

 by experiments of considerable diversity, carried out in a number 

 of laboratories. 



The original experiment of Gurwitsch was done with the roots 

 of onions. One root was held in a horizontal position close to 

 and pointing directly toward another held in a vertical position. 

 After some hours, the tip of the vertical root, the so-called 

 receptor, was "fixed" (killed with chemicals), sectioned, and 

 subjected to microscopic examination. It was found that in the 

 receptor root there were more cells in the process of division on 

 that side which had faced the sender than on the opposite side, 

 indicating that the sender root had radiated some form of energy 

 which accelerated cell division, or growth, in the receptor. 



Gurwitsch rays are not limited to the onion; they appear to 

 be characteristic of all living matter under certain (metabolically 

 active) conditions. That this is true is indicated by the long 

 and varied list of tissues so far known to radiate. The following 

 cells, tissues, and organisms have been shown to be sources of 

 radiant energy: bacteria, yeast. Hydra, the eggs of lower animals, 

 plant seedlings, potatoes, beets, blood of man, frog, and rat, 

 cancerous tissue, muscle, nerve, the brain of young axolotls, a 

 mash of Drosophila larvae, a mash of tadpoles, and regeneration 

 processes after amputation in tadpoles. Malignant tumors 

 emit rays in the strongest fashion; benign ones, less. 



A very important feature of the radiation, which answers a 

 question that must inevitably arise in connection with the trans- 

 mission of the energy through tissue, is that of secondary radia- 

 tion. It is the key to the whole problem. Without it there 

 can be no induction effect, as surrounding tissue would rapidly 

 absorb the radiation from within. Lacking secondary radiation, 

 the primary form would never reach the outside, except where 



