EXPLANATION OF PLATES IIL(rt) and IIL(A 



Postscript. — In bringing out the illustrations for my note 

 on the Septa across the ducts of Bougainvillea and Testudi- 

 naria, published in last part of the Society's Transactions, 

 I must apologise for the delay in publication, which was 

 due to various difficulties in their execution, difficulties to 

 which I need not particularly refer. As my communication 

 was little more than a memorandum of the structures I had 

 observed, I take this opportunity of adding a few remarks as 

 supplement. 



I have to regret my still very imperfect knowledge of the 

 literature connected with the two plants in question. As 

 to NijctafjincLcccc I have consulted Regnault's meD:ioir ^ on 

 the structure of the stems of " Cyclospcrmece," and the more 

 recent one of Petersen,^ who has made special and care- 

 ful study of the stem-anatomy of Nyctaginaccm. My study 

 of this latter work, has, I may say, from my ignorance of 

 the Danish language, practically been confined to his figures, 

 and to the French rcsumd accompanying the paper. I 

 have not had opportunity of seeing the works of linger ^ 

 and NsBgeli * to which Petersen makes reference. So far 

 as I can make out, however, the occasional septa across the 

 ducts of Bougainvillea have not previously been observed. 



Petersen gives a figure of a portion of a moderately young- 

 stem (perhaps of the second year) of Bougainvillea, showing 

 the central region with primary bundles, the outer zone 



^ Regnault, " Recherclies sur les affiiiites de Structure des tiges des plantes 

 du gi'oupe des Cyelospermees," i^7^/^. d. Sc. A^at., IV. Ser. (Botani(j[ue), tome 

 xiv. (1860). 



^ Petersen, " Bidrag til Nyctagine-sttengelens Histiologi og udvikliiigs- 

 liistorie," Botanisk Tidsskrift, xi. 149. Copenhagen, 1879. 



' Unger, Uchcr den liau uiul das Wachsthum des Dicotylcdonenstammcs 

 St. Tetersburg, 1840. 



* Nsegeli, Beitrdgc zur IVisscnscha/tl. Botanik, 1858. 



