BY WILLIAM J. BYRAM. 13 



These filame:ats are technically called flagella. They act as 

 propellers and their motion is so rapid that it is difficult to see 

 them. After swimming about actively for a time the cells come 

 to rest, draw in their flagella, develop a thick cell wall, and pass 

 into the resting stage, to recommence another life-cycle of the 

 same kind. I have called the protococcus a plant because it is 

 filled with the green colouring matter of plants, chlorophyll, and 

 because it obtains its nutriment as plants do by decomposing 

 carbonic acid gas, appropriating the carbon, which is one of the 

 elements of which that gas is composed, and giving off oxygen, 

 the other constituent. Animals, on the other hand, cannot feed 

 in this way, but derive their nourishment from already formed 

 organic matter, which they submit to a process of digestion. 

 Notwithstanding this distinction, we are now in the borderland 

 between animal and plant, and we find that there is no line of 

 demarcation between them. The* protoplasm of the amoeba, of 

 the sun-animalcule, of the human leucocytes is the protoplasm of 

 the yeast plant, of the protococcus, and of Tennyson's " flower in 

 the crannied wall." It is all very well to compare a wallaby 

 with a gum tree, and ask incredulously whether there is not a 

 very decided line of demarcation between animal and plant. 

 Look into your microscope again. Amongst the protococcus 

 cells ycu see a spindle-shaped body as brilliantly green as them- 

 selves. One end is blunt, or snout-like, and is furnished with a 

 long translucent filament or flagellum, just hke the flagella of 

 the motile stage of protococcus. It swims rapidly, and performs 

 peculiar contracting, expanding, and twisting movements as if it 

 were elastic. This strange body is a lowly animalcule, the 

 Euglena. It is a mere point of protoplasm — a single cell — and 

 we notice in its protoplasm the nucleus and the same remarkable 

 pulsating vacuole which interested us in the sun-animalcule. At 

 the snout-like end is a bright red pigment spot, which the 

 discoverer of the creature took for an eye, and from it chose the 

 Greek name Euglena, or bright-eyed. It is not even a 

 rudimentary eye, however, for though the Euglena is sensitive to 

 light, the greatest sensitiveness is in the other end of the cell, 

 away from the pigment spot. The Euglena has, however, really 

 the rudiment of a mouth, though it consists of but a simple 

 depression or groove into the soft interior protoplasm. Through 

 this depression minute nutrient particles are carried into the 

 interior. But the remarkable fact is, that while the Euglena 



