1885.] Observations on the Chromatology of Actinioe. 



85 



In the same way, the 9th partial was proved to exist, though the 

 beat was still faint. The beats for the 10th partial (flattening e'") 

 were better. 



On sharpening f", the beats of the 11th partial were just sensible. 

 They lasted such an extremely short time that they were recognised 

 with difficulty. It therefore did not seem worth while to try 

 further. 



These experiments conclusively proved the existence of the 5th, 

 6th, 7th, 8th, 9th, 10th, and 11th partials on a pianoforte string 

 struck with a pianoforte hammer at one-eighth of its length, and 

 that the 7th was comparatively powerful, while the 8th and 9th, 

 though faint, were distinct. The node of the 7th was 0*8 inch from 

 the striking place, and that of the 9th was 0'6 inch, so that the 9th 

 was more affected than the 7th, but the 10th was 1*1 inch from the 

 striking place, and hence probably was less affected than the 9th. 

 The curious point is that the 8th partial was most decidedly not 

 destroyed. 



These experiments were all witnessed by Mr. A. J. Ellis, and one 

 of Messrs. Broadwood's principal tuners, Mr. Pryer, who altered the 

 pitch of the strings as required. 



January 22, 1885. 



THE TREASURER in the Chair. 



The Presents received were laid on the table, and thanks ordered 

 for them. 



The following Papers were read : — 



I. "Observations on the Chromatology of Actiniae." By 

 C. A. MacMunn, M.A., M.D. Communicated by Professor 

 M. Foster, Sec. R.S. Received January 8, 1885. 



(Abstract). 



In this paper I have given the results of an examination of the 

 following Actiniae, mainly with regard to the spectroscopy of their 

 colouring matters, viz., Actinia mesembryanthemum, Bunodes crassi- 

 •cornis, Bunodes ballii, Sagartia bellis, Sagartia dianthus, Sagartia 

 parasitica, Sagartia viduata, Sagartia troglodytes, and Anthea cereus. 



The previous work of Moseley, Krukenberg, Geddes, the Hertwigs, 

 Brandt, and Heider, is first referred to. 



