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THE MEMOIRS OF A CAT
the scale of biological evolution. Modern surgery has gone farther. Not only is the human body rejuvenated through the grafting of thyroid glands taken from some lower animal; the operation cures mental and emotional exhaustion as well. Another set of emotions is connected with the pituitary glands. An injection of the serum prepared from this gland belonging to animals produces in man fear with all the bodily behaviour associated with this emotion.
All these and many other observed facts and experimental results have definitely led to the conclusion that spiritual properties are functions of the brain and of the central nervous system connected with it. Since a long series of biological forms lower than man are also possessed of these physical organs of spiritual activity, they cannot be denied the credit of the activity itself. This view is held by practically all the biologists and educated medical men of to-day.
Animal psychology is a very young science. Yet it has gathered enough data for the assumption that spiritual processes can be traced in all living beings far down the successive stages of organic evolution. Indeed, there is evidence of the process continuing even in the plants. It is as yet too premature to assert that plants feel pain, pleasure etc. But there are some experimental data showing that plants possess the power of response to stimulus, and are endowed with organs through
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