132 Sahni . — On Certain Archaic Features in the Seed of Taxus 
Cordaitales along the general tendencies outlined above, it is clear that we 
cannot strictly speak of a homology between the respective layers of the 
integument (outer flesh, stone, and inner flesh). A glance at the figure will 
show, for example, that in the so-called stone of Taxus there is nothing 
really comparable with the stone of Cardiocarpus. The region of the 
integument of Taxus which is comparable to the stone of the Palaeozoic 
type is no longer lignified and has become part of the inner flesh. It lies 
along a plane just inside the ‘ outer’ vascular system, and would be repre- 
sented by two lines joining the marks * * with the micropyle. In Taxus , 
therefore, what we are accustomed to call the 4 stone ’ is really homologous 
with a portion of the ‘ outer flesh ’ of the ancestral type. 
In comparing the seeds of the Taxales among themselves and with 
those of the Cordaitales the positions of the two vascular supply systems 
may safely be relied upon as determining the real homologies of the different 
parts of the integument. 
I wish to express my gratitude to Professor Seward for the kind 
interest he has shown in this paper by his able advice and criticism. To 
Mr. R. L. Lynch, M.A., Curator of the Cambridge University Botanic 
Garden, I am indebted for some of the material of Taxus baccata used in 
this investigation. I would also like to record my hearty thanks to Dr. Scott 
and to Mrs. Agnes Arber for valuable criticisms. To Dr. Scott I am further 
deeply indebted for his very generously lending me some of his best sections 
of Mitrospermum . Lastly, I have also gratefully to acknowledge Professor 
Seward’s kindness in reading the proofs of this paper. 
Botany School, Cambridge. 
April 7, 1919. 
Bibliography. 
Arber, Agnes (1910) : On the Structure of the Palaeozoic Seed Mitrospermum compressum (Will.). 
Ann. Bot., vol. xxiv, pp. 491-509. 
Bertrand, C. E. (1907 1 ) : Les caracteristiques du genre Taxospermum de Brongniart. Bull. Soc. 
Bot. France, t. liv, p. 213. 
(1907 2 ) : Les caracteristiques du genre Diplotesta. Ibid., p. 389. 
(1907 3 ) : Les caracteristiques du genre Leptocaryon . Ibid., p. 452. 
(1907 4 ) : Les caracteristiques du genre Rhabdocarpus d’apres les preparations de 
la collection de B. Renault. Ibid., p. 654. 
• — • (1908 1 ) : Les caracteristiques du Cycadinocarpus august odunensis de B s Renault. 
Ibid., t. lv, p. 326. 
(1908 2 ) : Les caracteristiques du genre Cai'diocarpus d’apres les graines silicifiees 
etudiees par Ad. Brongniart et B. Renault. Ibid., p. 391. 
(1908 s ) : La specification des Cardiocarpus de la collection B. Renault. Ibid., 
P- 454- 
Brongniart, Ad. (1874) : Etudes sur les graines fossiles trouvees a l’etat silicifie dans le terrain 
houiller de Saint-Etienne. Ann. Sci. Nat,, Bot., xx, p. 234. 
(1881) : Recherches sur les graines fossiles silicifiees. Paris. 
