1888.] Aluminium in certain Vascular Cryptogams. 121 



assumes the form of a mace, and later the anterior end further 

 expands to form a relatively large disk, while the remainder of the 

 original fibre persists as a slender ribbon- shaped appendage. As the 

 head of the club enlarges to form a disk, it passes through an indis- 

 tinct cup stage, which somewhat resembles the cups of the adult Baia 

 fullonica, hence it may be inferred that in Baia fullonica the organ 

 has been arrested in its development. The conversion of the muscular- 

 fibre into a club is largely caused by the increase at its anterior end 

 of muscle corpuscles. These corpuscles eventually arrange themselves, 

 either in front of the head of the club, to give rise to the electric 

 plate, or they migrate backwards to form at the junction of the head 

 of the club with its stem the alveolar layer. The striated layer, which 

 is from the first devoid of nuclei, seems to be derived from the anterior 

 striated portion of the club. 



The gelatinous tissue between the disks and the connective tissue 

 investing them, are derived from the embryonic connective tissue 

 developing disks. 



III. " On the Occurrence of Aluminium in Certain Vascular 

 Cryptogams." By A. H. Church, M.A., F.C.S. Communi- 

 cated by Dr. J. H. Gilbert, F.RS. .Received March 

 1888. 



Most of the older and fairly complete analyses of plant-ashes dis- 

 closed the presence of alumina in sensible quantities. Gradually, 

 however, as analytical methods became more exact, it was generally 

 recognised that this constituent had been derived from extraneous 

 sources and not from the plants themselves; alumina had in fact been 

 introduced by the employment of glass and porcelain vessels, of 

 impure reagents, and of imperfectly cleansed vegetable products. 

 Even when traces of this oxide were obtained in analyses conducted 

 under the most favourable conditions, an adventitious origin was 

 assigned to them, and so the item of alumina disappeared entirely 

 from the tables of the constituents of plant-ashes. Yet there were 

 some conspicuous exceptions, although these were confined to certain 

 cryptogams. For Ritthausen in 1851 (' Journ. Prakt. Chem.,' vol. 53, 

 p. 413) found " much alumina" in the ash of Lycopodium complana- 

 tum, Linn., while Alderholdt in 1852 ( k Ann. Chem. Pharm.,' vol. 82, 

 p. Ill) determined the percentage of alumina in the ash of the same 

 Lycopodium to be 51*85 in the plant when gathered in March, and 

 57*36 when collected in November. The same chemist found 26*65 

 per cent, of alumina in the ash of Lycopodium clavatum. Again, in 

 1856, Solms-Laubach found ('Ann. Chem. Pharm.,' vol. 100, p. 297) 

 in the ash of L. clavatum 27 per cent, and in the ash of L. complana- 



