YampolskY: Stiidy of OU palni. 16Q 



Fig. 10. A somcwhat older leaf sccn froin tlie front. Tlic Icaficts are defiiiitely 

 deliiniiiatcd. The invertcd Y is thé strip which holds the Icaficts togethcr 

 by their apiccs. The two anus of the Y arc attaclicd to scvcral of the 

 lower leaflcts in the respective halves of the leaves. The Icg of the Y 

 mari<s the boundary fine betwecii the iippcr leaflcts of the respective 

 halves. X 60. 



I.ike Figure 10 but sccn from the side. Note parallel arrangement of 

 leaflets. X 60. 



A still later stage. Leaflcts hâve begun to shift upwards. Note the criss- 

 cross arrangement of the fibres in the slicath and the parallel arrangement 

 of the fibres in the pétiole. X 25. 



Later stage showing the leaflets obliquely arranged. Near the base of the 

 leaf blade more leaflets are being added. Strip holding leaflets seen to 

 the right. X 25. 



A still later stage with leaflets showing various stages of elongation. X 1. 

 Portion of leaf from two year old plant in same stage of development as 

 Figure 14, showing the prolongations from the leaflets at S. Thèse prolong- 

 ations are madc up of the tissue of the leaflet proper and the remains of 

 the strip. X 30. 



Fig. 16. Half of a leaf blade showing the "Wiilste" of Nal'MANN and the slits of 

 Von Mohl. The parallel arrangement of the leaflets and the strip holding 

 them to-gether is seen. X 90. 



Fig. 17. Several leaflets from stage in Figure 16. X 100. 



Fig. 18. Longitudinal eut through leaf from 5 year old plant showing the large 

 number of leaflets in one half of a leaf. Strip is prominent. Note the 

 shifting of the plane of position of the upper leaflets in contrast to the 

 youngest and-smallest one. X 25. 



Figures 19, 20, 21. Leaflets showing triangular form. X 30. 



PLATE III. 



Fig. 22. Longitudinal section through growing point and leaves in various stages 

 of development. The Vs arrangement accounts for the various appearances 

 of the leaves AA, BB, CC, DD, etc., parts of individual leaves. X 60. 



Fig. 23. Longitudinal section through growing point showing origin of leaf 'Anlagen' 

 meristematic régions designated by the denser areas. X 90. 



Fig. 24. Leaflets in various stages of progressive splitting. It aiso shows the older 

 leaflets shifting from the horizontal to the vertical. Lower and younger 

 leaflets still horizontal. X '20. 



Fig. 25. Section of a lower portion of a leaf blade showing splitting of leaflets. X 120. 



Fig. 26. Leaflets splitting. X 120. 



Fig. 27. Leaflets developing within tissue of mother leaf. 



Taken from a stage like GG in Figure 22. X 160. 



Fig. 28. The next older leaf after the one in Figure 27, represented by HH in 

 Figure 22. The leaflets are seen within the tissue of the leaf blade. The 

 bounding area of the leaflets is the epidermis. Bundles connect with the 

 leaflets. X 160. 



Plate IV. 



Fig. 29. Growing région with youngest leaf 'Anlage'. The more strongly dotted 

 area shows the région from which the next leaf is to be eut off. X 60. 



Fig. 30. Young leaf 'Anlagen' seen from above showing beginning of growth of 

 the ends until they ultimately meet. X 60. 



