537 



spicules, which made some of the most fascinating microscopic 

 objects it was possible to imagine. 



Mr. F. Whitteron said the specimens he Lad brought had 

 been identified by a Fellow of the R.M.S., so he could specik with 

 authority as to their specific identity. He had received them 

 from Mr. M. J. Allan, of Geelong, who had collected them in 

 Corio Bay. 



The President said that Mr. Whitteron had also brought for 

 distribution some Globigerina collected from rocks at Geelong. 

 He would suggest that it was possible that the Geelong form of 

 Trochodota might be slightly different from the New Zealand 

 form. 



The thanks of the Club were voted to Mr. Whitteron. 



The Hon. Sec. read a note from iMr. E. M. Nelson on the 

 so-called pseudopodia of diatoms. The first notice of these, so far 

 as could be traced, is by W. W. Wood, Monthly M. Journcd, 

 vol. xiv. p. 255 (fig.)') I'^'SS. Next by J. Badcock, Journal R.M.S., 

 vol. iv., ser. 2, 1884, p. 352 (fig.) on Surirella hifrons. Then a 

 notice by{J. G. Grenfell, Journal R.M.S., 1893, p. 806, and 1894, 

 p. 415. Mr. Nelson wrote that he saw Mr. Grenf ell's exhibits 

 both at the R.M.S. meeting, and subsequently in his own study. 



The Hon. Sec. (W. B. Stokes) read a paper " On Resolutions 

 obtained with Dark-Ground Illumination and their Eelation to 

 the ' Spectrum ' Theory." 



Mr. A. E. Conrady, F.R.A.S., said that in his original paper 

 (read March 2Gth), on dark-ground illumination, he carefully 

 avoided expressing any definite number of lines per inch. Any 

 such statement brings one on to very difficult ground. Referring 

 to the difficulty of critically testing a theory, he said that it was 

 usually thought that a theoretical man works it out and leaves 

 the matter so that any practical man can test it. But it is 

 exceedingly difficult to test any theory so closely. The results 

 given by the objective of 0*86 N.A., using light of wave-length 

 5,000, agree very well with the figures he (Mr. Conrady) had 

 already given. The actual difference between Mr. Stokes's figures 

 and his own was that between 55 and 60, while the differences 

 between Abbe and Airy are as much as between 57,000 and 

 80,000 (lines per inch). It is very difficult to arrive at a defini- 

 tion of the limit. Can any worker be sure that he is really 

 working under the conditions laid down by either theory ? The 



