EMBRYOLOGY 



393 



I-'HJ. 2:4. 



Embryo of Equisi-tiiin. I. -IV., Kqitisetinii arrv/tji; L. I. and [I., the same embryo 



in different positions : in I. the median wall is visible, in II. the transverse wall. X 300. 

 III. -IV., a more advanced embryo showing development of the stem and leaf-sheath. 

 X25O. V., an embryo still further developed, but not dissected free from the prothallu*, 

 and showing the orientation relatively to the arche^oniiiiii. sf = the stem apex ; r-the 

 first leaf-sheath; > = the root. Xg8. VI. and VII., Kquisctuin paiustrt, L. VI.- 

 young embryo still in the archegonium, stem and foot are visible. X 300. VII. =an 

 embryo further advanced, and dissected free, and orientated 90 as compared svith VI. 

 The root (<) and stem (st) are visible. X 300. b = basal wall ; 7'= transverse wall ; m 

 median wall; f = epibasal and /; = hypobasal region; r' = the first leaf-sheath. (Aftei 

 Sadebeck, in Engler and Prantl, .\'a/. r/lmizenfain.} 



