Fig. 17. Enibryogeny in the Anthocerotales 

 A-D, Anthoceros fusiformis. A, Development of sunken archegonlum behind the 

 apexofthethallus. B, The undivided zygote. C, The first, vertical wall. D, The first 

 transverse wall. E-K, Anthoceros pearsoni. E, Young embryo in l.s. F, Segmenta- 

 tion pattern as seen in cross-section. G, Older embryo in l.s., showing foot develop- 

 ment. H, J, Two stages in the development of the segmentation pattern, in cross- 

 section. K, Older embryo in l.s. showing diff'erentiation of archesporium and 

 development of haustorial foot. L, A. fusiformis. Germinating spore showing 

 growth of thallus by an apical cell and characteristic segmentation pattern. M, 

 Notothylas orbicularis. Four-celled embryo. N-Q, Notothylas breutelii. Stages in 

 the development of the sporophyte as seen in l.s. R, Notothylas orbicularis. L.s. 

 through base of sporophyte, showing the enlarged cells of the foot. (A-M, R, after 

 Campbell; N-Q, after Lang.) (A-D, x 400; E-K, x 200; L, x 170; M, x 300; 

 N-P, X 350; Q, x 250; R, x 200.) 



