42 LABORATORY PRACTICE CHAP, vi 



2. The number of leaves through which the spiral passes 



to the leaf directly above the initial leaf. 



3. The number of revolutions of the spiral. 



4. The fraction expressing the phyllotaxy. 



X. Arrange the fractions found thus far in a series, and 

 notice that we may determine the third one found, by adding 

 together the numerators of the first and second to make its 

 numerator, and the denominators of the first and second to 

 make its denominator. Notice also that the fourth may be 

 formed in the same way from the second and third. 



What would be the fifth, sixth, etc., of this series? 



XI. Examine a cone of the Norway Spruce or of some 

 species of Pine. Notice : 



1. The scales of the cone (being really modified leaves) are 



closely packed together, and it is difficult to determine 

 the original spiral. 



2. Two series of secondary spirals, however, appear, one 



series running from left to right, and the other series 

 from right to left. 



3. Count the number of secondary spirals running from left 



to right. 



4. Count the number of spirals running from right to left. 



5 . Beginning with some scale near the base, number (in ink) 



this scale i. 



6. Number the next scale in the same secondary spiral run- 



ning to the right i plus the number found in 3, the 

 next one this number plus the number found in 3, and 

 so on. 



7. Beginning again with scale number i, number the next 



scale in the secondary spiral running to the left i plus 

 the number of spirals found in 4, and so on. 



