102 SIXTH RiiPORT— 1836. 



from its north and south sides gave 44 annual rings in the inch, so that 

 its radius would contain 2486 such rings, supposing them of equal 

 thickness throughout ; but making the same deductions as before, its 

 present age may be estimated at about 2006 years. 



This examination shows the Gresford yew to be about 200, and that 

 at Darley about 650 years older than De Candolle's standard of one 

 line per annum of the diameter would indicate, and consequently that 

 for old trees his average is too low. It also shows that the Darley tree, 

 with a greater diameter than the other of only 11 inches, is 587 years 

 older, the excess arising from the extreme thinness of its annual de- 

 posits. No precise rule can therefore be laid down, and actual sections 

 must be resorted to if anything like accuracy be required. Even this 

 plan is liable to errors, unless sections from ditFerent sides of the tree be 

 obtained, owing to the great and constantly recurring inequality in the 

 thickness and parallelism of the lings. The same ring often alternately 

 swells out and contracts several times in the course of its circuit round 

 the trunk, and groups or fascicles of rings also do so as if by common 

 consent, while other neighbouring series or individual rings, both within 

 and without, will be thickest where the first were thinnest, and vice versd. 

 Other sources of error are also pointed out. 



Mr. Bowman considers the custom of planting the yew in church- 

 yards to be of very high antiquity, anterior even to the introduction of 

 Christianity. It is well known that this tree was used by our Pagan 

 ancestors as a substitute for the cypress, both in religious rites and to 

 place upon the graves of their deceased friends ; it was indeed consi- 

 dered scarcely less sacred than their temples near which it was planted. 

 On their conversion to Christianity these temples were not destroyed, 

 but by an express order from Pope Gregory were converted into Chris- 

 tian churches, the better to reconcile them to the change. For the same 

 reason the sacred yew remained unmolested. 



Abstract of Observations on the Marsiliacea. By G. Lloyd, M.D. 



Finding in authors many contradictory statements on the nature 

 of the organs of reproduction in this small but interesting order o'f 

 plants, and having last year, for the first time, had an opportunity of 

 examining PiVw/ftrfa globulifera, the only British species (since Isoetes is 

 transferred to the Lycopodiacese), Dr. Lloyd was induced to endeavour 

 to ascertain their true nature. 



Without going into a lengthened detail of the structure of the 

 involucre and its contents, it is necessary to state that when opened it 

 is found to contain two distinct kinds of seed-like bodies, differing in 

 size, shape and structure, the larger being the true seeds, and the small- 

 er appearing to perform an office similar to that of the anthers of phse- 

 nogamous plants. The smaller bodies make no discernible attempt 

 at germination under any circumstances. The seeds of Pilularia germi- 

 nate when taken from the involucre previous to its natural bursting, and 

 when entirely separated from the smaller bodies or granules ; so that if 

 any impregnation be essential to the perfecting of the seed, it must take 

 place within the involucre, and not after dispersion in water, as some 



