1006 PROCEEDINGS OF THE SOCIETY. 



and measured tlie proportionate diameters of the outer and inner 

 portions, and from the figures given it was clearly shown that the 

 larger spines had the thinner crust. It was also found by taking 

 measurements from various parts of the spine that the wearing 

 down was not confined to the points. He was not prepared, however, 

 to give an answer as to how the interior of the spine increased in size, 

 though it was shown that in a full-grown specimen the interior cavity 

 was not diminished by the fact that it had a comparatively thick crust. 

 With regard to the growth of parasites, that necessarily had to be 

 taken into consideration as a matter of some importance, and though 

 of course he did not pretend to put his experience against that of 

 Dr. Carpenter or Prof. Stewart, he might say that if he had to base 

 his experience upon the large collection in the British Museum, he 

 should not have been struck with the amount of parasitism apparent 

 there. The crust had had ascribed to it a determining influence 

 upon the growth of the spine, but he ventured to think that the 

 figures which he had drawn gave a somewhat different aspect to the 

 question from that which had been hitherto accepted. 



Dr. J. D. Cox's paper " On Some Photographs of Broken Diatom 

 Valves, taken by Lamplight," was read (see p. 853), and the photo- 

 graphs accompanying it were handed round for inspection. 



Mr. J. Mayall, jun., and Mr. Crisp called attention to the points 

 in the photographs establishing Dr. Cox's views. 



Mr. Lewis "Wright exhibited in operation and described a new 

 lantern Microscope which, after considerable study and attention, he 

 had been successful in bringing to a degree of perfection which 

 he believed had not hitherto been attained. The want of some 

 apparatus of the kind capable of exhibiting minute objects under 

 high powers and free from distortion or colour had long been felt, 

 and he had been urged by several Fellows of the Society to turn his 

 attention to the matter on account of the great value to lecturers and 

 others of some really good optical arrangement which would enable 

 microscopical preparations to be properly shown to a large number of 

 persons at the same time. Dr. Carpenter had suggested to him to 

 take the tongue of a blow-fly, as prepared by Mr. Topping, and to 

 work upon that as a test object, and Mr. Curties had told him that 

 what was wanted was an apparatus which would show the tongue of the 

 blow-fly six feet long. He had placed the mechanical arrangements 

 in the hands of Mr. Herbert C. Newton, who had carried them out in 

 a way which left little or nothing to be desired. The lantern employed 

 was an ordinary one, the lime-light being used for illumination. As 

 regarded the objectives, he need hardly say that perfection in these 

 was of the first importance, particularly in the case of the higher 

 powers, as many a lens which seemed to work very well upon the 

 ordinary Microscope would completely break down under the strain 



