646 SUMMARY OF CURRENT RESEARCHES RELATING TO 



mediate between the normal and callus-buds, formed on normal roots 

 from callus, but without any previous injury. In the former case they 

 spring from the parenchyma of tho secondary cortex around the origin 

 of tho lateral roots ; in the lattor case by tho metamorphosis of 

 dormant lateral roots which have remained within the secondary 

 cortex. The same has been observed also in Solarium Dulcamara and 

 Brassica oleracca when pulled up and replanted upside down. Apices 

 of roots form leaf or flower-buds in (Jphioglossum, Selaginclla, Plaly- 

 cerium, Neottia nidus-avis, Cataselum, Anthurium, Dioscorea, Viola 

 sylvestris, and Balsamina. 



In almost all plants which produce root-buds the mode of origin 

 is accompanied by some morphological peculiarity; only in the most 

 nearly related species is it altogether or even nearly identical. 



Dr. Bcyerinck classifies root-buds according to the tissue in which 

 they arc formed, viz. either immediately below the growing apex of 

 the root, in the pericambium, or from the older parts ; and in this 

 case either by direct metamorphosis of a dormant rudiment of a root, 

 or from that part of the primary cortex of a lateral root which still 

 remains imprisoned in the cortex of the mother-root, or thirdly from 

 the merismatic layers which lie beneath the secondary periderm after 

 the primary cortex has been thrown off, or beneath the suberous layer 

 which clothes the primary cortex. The author gives a number of 

 illustrations of the varieties of these different primary groups. In 

 most Podosteniacea) the branching appears to depend mainly on the 

 formation of root-buds, corresponding in their position to the two 

 xylem-bundlcs of the biradiate root ; they are formed in the central 

 part of the primary cortex quite independently of the central 

 cylinder. 



Serial Buds.* — According to M. J. Velenovsky, serial buds occur 

 normally in dicotyledons, while in monocotyledons he has observed 

 only a single case. They occur as buds on all the permanent axes, 

 frequently as branches in the inflorescence. In some plants (Ijonicera, 

 Sambucus) they arc found in every leaf-axil ; in others (Fagus, 

 Carpinus) only on luxuriant shoots. In Kaplianus Baphanistrum there 

 are not unfrequently as many as five serial branches in the axil of 

 the leaf, carrying the subtending leaf with the last shoot far from the 

 main stem. The development of these buds can be followed out well 

 in Bobinia Pseudacacia ; the serial buds are subordinate to the first 

 bud, but are formed in the same way, and originate from the same 

 cell-tissue. The first axillary branch always dies in the following 

 year, and then the first serial bud developes into a branch. 



The function of these serial buds is to form a reserve in case 

 of the loss of the first bud ; sometimes they develope into vegetative 

 axes, sometimes into flowers. 



Anatomical Structure of Senega-root, f — Herr O. Linde describes 

 in detail the structure of the root of Polygala Senega, which presents 

 several peculiarities. The medullary rays are all in connection with 



* See Bot. Centralbl., xxvi. (1886) p. 10 (original in Bohemian), 

 •f Flora, Ixix. (1886) pp. 1-32 (1 pi.). 



