of the External Coatings of Seeds. 279 



an expansion of the placentary sheath, I have called an arilline^, 

 to distinguish it from the true arillus, which is always more ex- 

 terior to it, and not necessarily fleshy, and which is an emana- 

 tion from, or growth of, the funicle. If the term arilline, which 

 is identical with the arillode of Planchon and the faux arille of 

 St. Hilaire, be objected to, it is easy to give it another name ; 

 but that coating, in no case, can be considered to be the testa, 

 though sometimes confluent with it. 



These considerations are perfectly consistent with the doc- 

 trines of Brown and Mirbel, now universally adopted by botanists, 

 in regard to the development of the coats and nucleus of the 

 ovule and the mode of its fertilization and growth. 



The question in regard to the seed-coats of Magnolia having 

 been fully discussed in my former paper f, I need only here refer 

 to the main points at issue in that case. Dr. Asa Gray, having 

 at first overlooked the existence of the inner integument, was 

 led to conclude that the two outer tunics of its seed are the 

 growth of the two coats of the ovule J ; but he afterwards ad- 

 mitted that its bony shell must be held to be its testa § ; at the 

 same time, not prepared to renounce his favourite prepossession 

 that the scarlet coating is a growth of the primine, he main- 

 tained that the two constituted one integral tunic, " a baccate 

 testa :'^ this term, of no definite meaning, was invented by Lin- 

 nseus, prior to the existence of any distinct nomenclature being 

 given to the several tunics, and before their nature and origin 

 were inquired into. Gaertner, in the use of this term as applied 

 to Magnolia, explains that its testa is covered by a fleshy envelope 

 analogous in its nature to that of an arillus, and in describing 

 the seed of that genus, he defines its envelopes as consisting of 

 three distinct tunics ||. Drs. Hooker and Thomson had in the 

 meanwhile adopted the opinion of Dr. Gray regarding the outer 

 seed-coats of Magnolia, and in this respect they diff'er from all 

 preceding botanists^. 



* Linn. Trans, xxii. 89. J Gen. Unit. States, i. 60. 



t Linn. Trans, xxii. § Hook. Kew Journ. vii. 244. 



II De Fruct. Intr. 133 ; vol. i. 343 ; Linn. Trans, xxii. 86. 



H This is denied by the reporter, in a marginal note made on my paper ; 

 but, with all the consideration due to that authority, I submit, as far as my 

 memory extends, that I know of no one who has previously entertained 

 the opinion of Dr. Gray, that this scarlet coating is the testa. Gaertner's 

 definition, here alluded to, is dated 1788; and those who subsequently 

 adopted the same expression would have explained their meaning, if they 

 differed from that definition. Jussieu, however (1789), distinctly confirms 

 Gaertner's explanation (Gen. PI. 281), when he ascribes to Magnolia 

 " semina baccata sen arillata." DeCandoUe, in his ' Systema' and ' Pro- 

 dromus,' adopts simply the same phrase " semina baccata," without further 

 explanation. Spach (Phaner. vii. 469) says positively "arille charnu.'* 

 EndUcher (Gen. PI. 473/) also defines it " integumentum exterius carnosum 



