1913] The Ottawa Naturalist. 155 



penetrated the atmosphere and reached the living protoplasm. 

 The simplest masses of protoplasm we are able to study are 

 minute spherical or elongated structures, with a firm boundary 

 or wall, or with a gelatinous envelope. These have two method's 

 of reproducing themselves, the simplest of which is by each 

 merely splitting into two fission. The other method consists in 

 the material which forms one mass breaking into many small 

 parts within the wall. These parts escape through a rupturing 

 of the wall of the parent cell. Each of these new individuals 

 seems to be exactly like all the others, and is independent of all 

 the others, doing for itself whatever is necessarv for its life. 



In examining the various one celled plants we are struck by 

 the fact that one great group of them has kept the habit of living 

 each by itself, a distinct individual life, while those of the other 

 group adhere to each other in irregular masses, or even form 

 carefully arranged colonies. We note that most of those that 

 retain their independence live in dark, moist, warm situations, 

 often within larger living creatures, and they accentuate their 

 individual liberty by moving from place to place, through short 

 distances. We call them Bacteria. They never reach any consider- 

 able size nor permanence of structure, but being bathed constantlv 

 in liquids w^hich yield them nourishment, they increase rapidlv 

 in numbers by the process of cleavage, each splitting into two, 

 and these again in a very short time. By this geometric pro- 

 gression they multiply at a prodigious rate, and we are aware 

 that their activity or the poisonous substances they excrete are a 

 menace to the lives of many of the higher creatures which they 

 inhabit. Fortunately for us they have not learned how to pro- 

 tect themselves against light, which when intense exerts a 

 destructive influence on colorless protoplasm. Another weakness 

 of bacteria, and the same is true of nearly all other kinds of 

 fungi, is that each individual is literally " a chip of the old block." 

 The parent really becomes rejuvenated in the form of two off- 

 spring made from its material. Let me ask you to note that this 

 is a form of immortality. Here there is no such thing as maturitv, 

 old age, and death. Each bacterium literally "renews its 

 youth" by making of itself two new bacteria. Each of these 

 must therefore retain unchanged the qualities of the only parent 

 it has. There is little chance of its receiving any influence which 

 will cause variation, and each is exactly of the character of the 

 line of parents preceding it. Its qualities are rigidly fixed in the 

 type of its ancestors. In this fixity of type and lack of adapt- 

 ability of the race of fungi we have an important character 

 which aids us when we desire to prevent their growth. If we can 

 modifv in any marked degree the conditions surrounding them, 

 we render their existence difficult, if not impossible. An illustra- 



