158 



GENERAL BIOLOGY 



existence is actually a part of all its ancestors, or to be more accurate, 

 it is its ancestors, for these ancestors have never ceased to be. This 

 must necessarily be true, because each ancestor merely divided into two 



offspring, the offspring thus being in reality 

 the parent itself. This is vastly different 

 from a parent giving birth to an offspring 

 and then dying. 



It is an established and incontrovertible 

 biological fact that no living cell can come 

 from anything but a previous living cell. 

 No organism or living thing can possibly 

 come into existence except from some pre- 

 viously existing living parent form. 



Now, if sufficient food is given Para- 



Fig. 81. 



Stage 



Paramotcium caudatum. A, Stage 

 A, the micronucleus in each gamete 

 preparing for division 



moecia they will keep on dividing several 

 B stage B hundred times, but then, if they are with 



the daughter nuclei in each gamete others of their kind an interesting- event 



dividing. C, Four micronuclei in 



each gamete. D, three of the four takes place. TwO of the animals Will SW11TI 



pas - ) 



micronuclei are disintegrating ; the r , . 



surviving nucleus in each gamete around and around, Finally attaching tnem- 



has divided to form d". 'the male, 1,1 i .1 i -i , 



and j. the female pronucleus. E, Selves to each Other length W1SC while the 



wa " of each animal that comes in contact 



with its mate seems to disappear, the two 

 animals becoming almost, but not quite, one 

 individual. 



The smaller colorable spot in each animal now begins to divide into 

 two parts as shown in the drawings. These parts again divide, making 

 four pieces to each nucleus. Three of these pieces disappear (probably 

 they are dissolved in the body substance), but the one remaining piece 

 then again divides into two pieces, one of which remains more or less 

 stationary while the other (often partially connected with the first) 

 moves toward the midline of the two connected animals to meet with 

 a similar movable piece of stainable matter from the attached individual. 

 The two pieces of movable-stainable-matter become one for a short pe- 

 riod, seemingly exchanging some of their substance, then they again 

 separate and go back to form a nucleus like the one from which they 

 sprang. 



The animals themselves now separate, and each begins its division 

 into two new animals, which again divide, such division continuing as 

 already mentioned, several hundred times, until this same conjugation 

 or joining process is brought about again. The larger stainable-spot is 

 dissolved at the time of conjugation and is thought to have some nutri- 

 ent function. 



It is the nuclear material which seems to be the important physical 

 matter in the formation of any living thing plant or animal and in 

 turn it is only the colorable matter inside the nucleus known as chro- 



