FORM OF THE VASCULAR FASCICULI IN BRITISH FERNS. 83 
That this is an advantage, and is one great end gained by reciprocal 
dimorphism, I can entertain no doubt. That in some cases this 
dimorphism may be a step towards a complete separation of the 
sexes, I will not dispute; but good reasons could be assigned 
to show that there is no necessary connexion between reciprocal 
dimorphism and a tendency to diccious structure. Although good 
is gained by the inevitable crossing of the dimorphic flowers, yet 
numerous other analogous facts lead me to conclude that some 
other quite unknown law of nature is here dimly indicated to us. 
On the Form of the Vaseular Fasciculi in certain British Ferns. 
By Arruur H. Cuurcu, B.A. Oxon. Communicated by 
W. Francis, Ph.D., F.L.S. 
[Read Dec. 18, 1862.] 
Tux distribution of the vascular tissues in the stem and stipes of 
the British species of Ferns has been made the subject of much in- 
teresting and accurate study by Dr. Ogilvie*. His papers are to 
be found in the ‘ Annals and Magazine of Natural History’ for 
December 1859 and November 1860. My own long-continued 
examination of the living plants has not enabled me to detect any 
but the most trivial mistakes in these full and admirable memoirs. 
I have therefore only to propose a few slight alterations in Dr. 
Ogilvie’s conclusions, and to make one or two additional remarks 
on certain species and varieties which he omits to notice. The 
present communication may be deemed the first instalment of 
such supplementary observations. I may also here state that I 
* The following list of papers includes nearly all those in which the vascular 
tissues of Ferns have been discussed :— 
Presl. Tentamen Pteridographim. Prage: 1836. 
Fée. Die Gefiissbiindel im Stipes der Farne. Prage: 1847. 
Ogilvie, Dr. Ann. & Mag. Nat. Hist. 1859 and 1860. 
DuvalJouve, J. Etudes sur le Pétiole des Fougères. In Billot’s Archives 
de la Flore de France; pp. 57 & 149. 
King. On Sigillaria. Edinburgh Phil. Trans. 1844. l 
Leighton, Rev. W. A. Hints on a new character in Ferns. Phyt. n. s. i. 
p. 256. 
Moore, T. The Vascular Bundles of the Stipes of Ferns. Phyt. n. s. i. p. 378. 
Reichardt, H. W. Ueber der Gefüssbündel Vertheilung im Stamme und 
Stipes der Farne. Denkschriften der Kaiserlichen Akademie der Wissen- 
schaften, xviite Band. Wien: 1859. 
