272 



IIOFMEISTER, ON 





^ 2 

 hh.3 



-3 

 Gl 





h3 



Iu the 5th. 

 In the 6th. 



In the :12th. 



a 



4 



a 



b 



a 



b 



a 



j 



a 



b a b a 



i | 



h 



In Equiselum palustre (a vigorous 



shoot) 4 



< The same species, a very delicate 



4 

 5 

 4 

 4 

 4 



4 

 4 

 8 

 4 



4 



7 



32 



8 



4 

 5 

 8 

 6 



6 



7 



4 



7 

 8 

 4 



4 



7 



40 

 9 



7 

 9 



10 

 7 



6 



7 



4 

 9 



8 

 4 



4 



7 



48 

 12 



8 

 12* 



17 



7 



7 

 13 



4 



8 



! i 











Eg. limosum (a shoot formed at 

 the end of May) 



Eq. limosum (a vigorous autumn 

 shoot) ..... 



Eq. prate?ise (a vigorous autumn 

 shoot) ..... 



Eq. variegatum (a delicate shoot) 



The number of cells of the trans- 

 verse diameter iu a vigorous 

 autumn shoot of Eq. limosum 

 amounted to . 



In a delicate shoot of Eq. variega- 

 tum to . 



4 

 4 



4 







i 





4 



4 



10 



7 



1 



JlO' 8 



1 ; 



13f 



3 ? 





! 





22 

 5 





58 

 12 



... 













12 



... 





...j 



This comparison appears at the first glance to be quite at 

 variance with the common notion that the cells of the stem 

 are multiplied in a longitudinal direction only at the apex 

 of the organ. This opinion is untenable in any extended 

 sense. As far as observations go there are no plants, from 

 the mosses upwards, in which the cells of the stem are mul- 

 tiplied in a longitudinal direction exclusively by division 

 of the terminal cell. Generally the division of the daughter- 

 cells of the cells of the second degree by septa at right 

 angles to the longitudinal axis, plays an important part in 

 the production of longitudinal growth. On a more accu- 

 rate examination, however, the above table, shows that 

 there is a special tendency to multiplication in the cells of 

 those parts of the leaves which have been already some 

 time formed. It is only the cells of the cortical layers 

 (which my figure PI. XXXV, fig. 1, shows clearly to have 

 been produced by the multiplication of the cells of the leaf- 

 rudiment) which exhibit the long- continuous longitudinal 



* Those of the epidermis 14. This fourth internode exhibited the first 

 indications of annular vessels, 5 — 6 rings iu each of the cells of a longitudinal 

 row adjoining the pith. 



f A trace of annular vessels was first visible iu the loth internode. 



