3l6 
Proceedings of the Royal Irish Academy ^ 
and no "root-hairs" as yet formed, the only next immediate source of 
nutriment for the growing hypha would, I imagine, in the experiment 
of Reess, appear to have been the ''Nostoc-jelly." I^ow a " Palmella- 
jelly," or a " Mesotaenium-jelly" (both aerial, that is, not under water), 
woiild seem in themselves to be possibly just as likel}^ to afford the 
qumte pabidiim for the germinating and growing Collema-spore. If 
this conjecture should be borne out, M^hich I would indeed put with all 
diffidence, what would be the result of Reess's experiments, or rather, 
what proven thereby ? Such a combination (if capable) witli a Pal- 
mella or a Mesot^enium would not be " Colleraa," because it would not 
have " nostochaceous" gonidia, nor the characteristic periderm. If, 
indeed, we might for a moment assume that which direct experiment 
alone could prove, and a germination of spores and penetration of the 
hypha of a Collema with a Mesotsenium effected, such a lichen- thallus" 
would be, I apprehend, unprecedented — a hypha likj other lichen =- 
h5'ph[e, no doubt (but hioivn to be that of a Collema), with large ellip- 
tical or cjdindrical "gonidia" containing a central "chlorophyll-plate," 
and which would probably (in free nature at least, even though 
accompanied by the hypha,) go on and produce zygospores ! 
I trust that the reader of the foregoing remarks will understand that 
I put them forward but with a great amount of diffidence ; it was 
the occurrence of my little spore-bearing ISTostoc, which suggested to 
me to venture to do so. Isolated, indeed, as was that example, still no 
matter from what aspect viewed, even though it be urged that we 
should look upon it as " abnormal" on account of its rarity, it cannot, 
I apprehend, but be regarded under any circumstances as to a certain 
extent suggestive and as possessing at least some amount of significance. 
XXXVL— Oisr A IS'ew Appeoximation to the Orbit of the Bustaey 
Stae, ^ Uesae Majoeis. By Robeet Stawell Ball, LL.D., 
M.R.I.A. With Plates XXII. & XXIII. (Science). 
[Eead June 24, 1872.] 
The orbit of this star has been computed by Savary, ' ' Connoiss 
des Temps." 1830, by Herschel II., " Trans. Astronomical Society," 
Lond. Vol. v., p. 209, by Madler, " Dorpat Observations," Yol. IX., by 
Villarceau, " Astron. Xachrichten, Yol. XXIX.," and by others. It 
might appear that any further investigation of a subject which 
had engaged the attention of so many eminent astronomers was su- 
perfluous. It will, therefore, be necessary to recount the circum- 
stances which render a new determination of the orbit desirable. 
^ Ursae Majoris is a binary star, whose components are of the 4 and 5 5 
magnitudes respectively — (Smyth). The periodic time of this star is, 
probably, a little less than sixty years. The first recorded observation 
is by Herschel I., in the year 1781. The star has, therefore, been watched 
during the entire of one revolution, and half of another. All the com- 
putations of the orbit indicate that the star passed through periastron 
