90 



why it seems necessary for animals to die. 

 This short scene (it lasts only fifty-live 

 seconds) was 

 most difficult to 

 take. Three 

 whole weeks of 

 watchful wait- 

 ing were required 

 on the part of 

 the photograph- 

 er. He had to 

 observe the ani- 

 mals constantly 

 and to be pre- 

 pared to photo- 

 graph the divi- 

 sion when it oc- 

 curred. 



How the Yeast Cell 

 Reproduces 



Microscopic life re- 

 produces not only by 

 self-division but also 

 by budding. To bring 

 out that fact, the com- 

 mon yeast plant, used 

 in bread-making, was 

 chosen by Mr. Stone 

 as a motion-picture 

 subject. The yeast is a 

 one-celled plant. It 

 reproduces by a process 

 of budding which close- 

 ly resembles the divi- 

 sion which takes place 

 in the protozoan. The 

 yeast cells bud slowly. 

 In order to secure a 

 record of their growth, 

 the photographs were 

 made at intervals of 

 four and one-half min- 

 utes over a period of 

 twelve hours. Since 

 they are viewed at the 

 rate of sixteen per sec- 

 ond, the growth is wit- 

 nessed in the short 

 space of ten seconds. 



The film next ex- 

 hibits to us the repro- 

 ductive processes of 

 higher and more fami- 

 liar plants. It shows 

 that they reproduce 

 their own kind either 

 from cuttings or from 

 seeds. A slip of gerani- 



Popidar Science Monthly 



Section of the film 

 showing the devel- 

 opment of a rat's 

 embryo. All life 

 develops from cells, 

 in the same way 



um was planted. One photograph was 

 made every six hours. On the screen a 



To the left is an 

 enlargement of 

 one of the hun- 

 dreds of pictuics 

 made to show the 

 development of 

 the rat from the 

 embryo to the 

 living litter. 

 Since the rat is 

 a higher animal 

 and the processes 

 of life are ex- 

 plained from the 

 crudest to the 

 most complex 

 forms, this por- 

 tion of the film is 

 near the end 



growth is shown in one 

 second which took 

 place in four days. 



Most plants, how- 

 ever, develop from 

 seeds, and the seeds, in 

 turn, originate in the 

 flowers of the parent 

 plant. To bring out 

 that fact, photographs 

 and diagrams of the 

 sweet-pea are present- 

 ed to show how the 

 pollen grains from the 

 anthers fall on the 

 stigma and there pro- 

 ceed to grow and send 

 out tubes. The tubes 

 work their way down 

 through the coarse tis- 

 sues of the style until 

 they reach an ovule. 

 Then the whole process 

 of fertilization is re- 

 vealed^how the fer- 

 tilized egg cells become 

 peas while the pistil 

 of the flower becomes 

 the pod which sur- 

 rounds and shelters 

 them. 



Much more difficult 

 was the problem pre- 

 sented by the higher 

 animals. With them 

 life begins in a fertilized 

 egg cell. The first ani- 

 imal shown is the sea 

 urchin, close relative 

 of the starfish. On the 



The mother rat 

 coming out of her box 

 and picking up her 

 progeny one by one in 

 her mouth, dropping 

 them into the nest 



