1892.] and aiiiiiial and vegetable life. 11 



solar radiation is about ^^yth of what it is at the distance of the 

 earth. 



Again, Jupiter rotates on his axis in about 10 hours. We 

 will therefore assume that for places similarly on the two planets, 

 — 9^ for the earth is 27 x f^, or about 65 times as great as for 

 Jupiter. Thus, with the preceding assumptions, it follows that 

 the want of sunshine causes vegetation, and therefore food, to 

 be about 65^ x 27, or about 114000 times as scanty on Jupiter 

 as on the earth. With similar assumptions, it will follow that 

 vegetation and food are far scarcer on the further planets, Saturn, 

 Uranus and Neptune, even than on Jupiter. On such barren 

 wildernesses, animal life, as we know it, could hardly exist. 



(3) Note on the Geometrical interpretation of the Quaternion 

 Analysis. By J. Brill, M.A., St John's College. 



November 14, 1892. 

 Prof. T. IVFK. Hughes, President, in the Chair. 



The following were elected Fellows of the Society : 

 J. Y. Buchanan, M.A., Christ's College; 

 A. Hutchinson, B.A., Pembroke College. 



The President exhibited (1) a live Tarantula, (2) quartz crystals 

 of unusual form. 



Mr J. J. Lister exhibited preparations showing the division of 

 the nuclei in the sporangium of a species of Trichia, one of the 

 Myxomycetes. The nuclei divide throughout the sporangium 

 with clearly recognizable karyokinetic figures, immediately before 

 the formation of the spores. 



The following communications were made: — 



(1) On the Reproduction of Orbitolites. By J. J. Lister, M.A., 

 St John's College. 



Mr H. B, Brady has described specimens of Orbitolites, which 

 he obtained in Fiji, showing the margin of the disc crowded with 

 young shells. Mr Brady's material was worked at in the dry 

 state, and it was at his suggestion that the author collected speci- 

 mens preserved in spirit from the Tonga reefs. 



Examination of this material shows that large brood chambers 

 are formed at the margin of the disc during the later stages of 

 growth. These are at first lined with a thin layer of protoplasm. 

 At a later stage the central region of the disc is found to be 

 empty, and the whole of the protoplasm is massed in the brood 

 chambers in the form of spores. The spores have the structure 

 of the ' primitive disc,' which during the early stages of growth 

 of the Orbitolites occupies the centre of the shells. They are 



