FORMS OF LIFE. 47 



62. Compare this classification with that in Section 59. 

 Is "this a true equation i + 2 =A + B? 



Is i the exact equivalent of either A or B? Is i greater 

 or less than A? Is 2 greater or less than B? Give your 

 grounds for your various answers. 



If you should divide the group of plants into A =A* + A 2 , 

 in which A 1 equals green plants and A 2 the non-green 

 plants, could you make i =A true by adding or sub- 

 tracting A 1 or A 2 ? 



Translate these expressions into a plain statement 

 of truth and see if they hold good so far as your observa- 

 tions and information go : i = A - A 2 =A* ; also 2 -= B + A 2 . 



Devise some sort of a diagram to express the truths 

 indicated by these algebraic formulae. 



Where would the mistletoe fall in the classifications 

 you have been making? Why? 



63 . Exercises for Further Research. -i . Make a classi- 

 fication of the organisms you know, on the basis of their 

 food relations; that is, as to whether they can be in- 

 dependent of organic food or not; and if they must have 

 organic food, whether they use vegetable food or animal 

 food; whether they use dead or living food; whether 

 they are parasites, semi-parasites, or predatory forms. 

 Where would man fall in this classification? 



2. Are bacteria plants or animals? What grounds 

 do you have for your answer? To what facts do these 

 other terms, applied to the same organisms, refer: 

 germs, microbes, organic ferments? 



