Varietäten, Descendenz, Hybriden. 19 



rays. In this process of reduction vestiges of the wide rays tend to 

 be more persistent in the peduncle, root, and nodal regions. 



c. The multiseriate ray a widened uniseriate ray. 



The multiseriate ray does not appear to be of recent origin, 

 since it is well developed in most tropical and temperate families 

 and extends through the tertiary at least to the Middle Cretaceous. 

 This type of ray structure originated in all probability by the gra- 

 dual increase in width of the primitive uniseriate ray. 



d. Phylogeny of the Amentiferae. 



One character, of course, cannot be considered conclusive evi- 

 dence for assuming that a plant or group of plants is "regressive" 

 or reduced, since all characters will not be similarl}'^ affected by 

 changes in the environment or physiological activity, but the reduc- 

 tion of Wide rays in the Fagales indicates that this order, as well 

 as the Casuarinaceae, has been subjected to a strong modifying in- 

 fluence. This fact, taken together with the occurrence of syncarpy, 

 epigyny, abortive ovules, and vestiges of bisexual flowers and floral 

 envelopes, emphasizes the importance of the frequentljT^ repeated 

 Suggestion, that the Atnentiferae, instead of being the most primitive 

 of angiosperms, are a group of specialized families, which have 

 reached their present more or less simple structure through reduc- 

 tion from earlier and usually more complicated forms. 



Jongmans. 



Coulter, J. M. and W. J. G. Land. The origin of Monoco- 

 tyledony. (Botanical Gazette. LVII. p. 509—519. PI. 28, 29. 2 

 Textfig. 1914.) 



The writers studied monocotyledonous and dicotyledonous seed- 

 lings of Agapanthiis unibellatus L'Her., from South Africa. The 

 dicotyledonous condition is rare, only one specimen was found. On 

 the writers' anatomical researches on these seedlings, on a compa- 

 rison with Sagütaria and on the results, obtained in Cyrtanthus 

 sanguineus by Miss FarreU, who found as developmental stages 

 four cotyledons, two cotyledons and finally one large, the following 

 conclusion is based. 



In both Monocotyledons and Dicotyledons a peripheral cotyle- 

 donary zone gives rise to two or more growing points or primordia, 

 and this is followed by a zonal development resulting in a cotyle- 

 donary ring or sheath of varying length. If both growing points 

 continue to develop equally, the dicotyledonous condition is reached. 

 If one of the growing points ceases to develop, the growth of the 

 whole cotyledonary zone is associated with that of the other growing 

 point, and the monocotyledonous condition is reached. In other 

 words, monocotyledony is not the result of the fusion of two coty- 

 ledons, or of the suppression of one; but it is simply the continua- 

 tion of one growing point on the cotyledonary ring, rather than a 

 division of the growth between two growing points. In the same 

 way polycotyledony is the appearance and continued development 

 of more than two growing points on the cotyledonary ring. In fact, 

 in Cyrtanthus four growing points appear at first,. which under cer- 

 tain conditions might result in four cotyledons. The whole Situation 

 has its parallel in sympetalous coroUas, in which there is zonal 

 development associated with three, four, or five separate growing 

 points, which, continuing development, are recognized as petals. 



It follows, that cotyledons are always lateral structures arising 



