PROCESSES OP LIFE REVEALED BY THE MICROSCOPE. 387 



action, and again the grannies begin to appear and increase in number 

 until finally the cells become so full that they are fully charged and 

 again ready to pour forth the digestive fluid. This is a daily, almost 

 an hourly process. (See Plate XIII.) 



Let us take another example in which it would almost appear that 

 there is organic memory on the part of the gland cells. No doubt all 

 have seen the clear jelly-like masses surrounding the eggs of frogs and 

 salamanders. Whence comes this jelly that is so resistant to the agents 

 that work so quickly the destruction of ordinary organic matter? As 

 spring advances the cells of the oviduct increase enormously in size. 

 The microscope shows this increase to be due to a multitude of clear 

 granules. As the eggs move along, the ova are coated with the jelly 

 formed from the granules given out by the cells. As this material for 

 the jelly is poured out the cells gradually shrink to their original size, 

 and then wait another twelve months before doing their destined 

 work. 



If one can thus catch a glimpse of some of the finer processes taking 

 place in gland action, how is it with nervous action, the highest function 

 of which living matter is capable? While it has been known for a 

 long time that the nervous system is the organ of thought and feeling 

 and the director and coordinator of the motions of the body, and many 

 speculations had been made concerning the processes through which 

 the nervous tissue passes in performing its functions, it was left to an 

 American student, Dr. Hodge, to first successfully show that there 

 were visible changes through which the nervous system passes in its 

 work. The question is, can the activity of the nervous system be traced 

 as surely by changes occurring in the living matter forming its basis, 

 as the action of a gland can be seen by the study of the gland cells? 



The demonstration is simple now that the method has been shown. 

 No doubt everyone has had the experience of failing to perform some 

 difficult muscular action at one time and then at another of doing it 

 with ease, or of finding true the reverse of the adage, "practice makes 

 perfect." For example, in a trial of skill, as in learning to ride a 

 bicycle, all the complicated action may be performed with considerable 

 ease and certainty at the beginning of a lesson, when one is fresh, but 

 as the practice continues the results become progressively less and less 

 successful, and finally with increasing weariness there is only failure, 

 and one must rest. We say the muscles are tired. This is true in part, 

 but of much greater importance is the fatigue of the nervous system, 

 as this furnishes the impulses for the action and coordination of the 

 muscles. Now, as muscular action can be seen and the amount can be 

 carefully controlled, here was an exact indicator of the time and 

 amount of the nervous activity. Furthermore, as animals have two 

 similar sides, one arm or leg may work and the other remain at rest, 

 and consequently corresponding sides of the nervous system may be 

 active and at rest. By means of electrical irritation one arm of a cat 

 or other animal was caused to move vigorously for a considerable time, 



