26 RAINEY, ON CARBONATE OF LIME GLOBULES. 



development. See fig. 5, whicli is a representation of the 

 otolithe of a young stickleback, and fig. 6 of one from a 

 very small whitebait. These bodies are formed by the 

 deposition of carbonate of lime in small sacs, which car- 

 bonate seems to go through the same changes of form as in 

 shells, but I have not found the globules presenting so well- 

 defined a cross under polarized light as in some forms of 

 shell. With respect to the manner in which the calcareous 

 globules, in the artificial process, acquire their increase of 

 size and become coalesced into one mass, I may notice 

 that the explanation given in my first paper is founded on a 

 theoretical error, which more accurate experiments and 

 more careful observations have since enabled me to correct. 

 In my first method of obtaining the globules of carbonate of 

 lime with gum, the different changes which these bodies 

 underwent being produced in bottles, were entirely out of 

 the reach of direct observation, and therefore the manner 

 in which these forms were produced must be, to some extent, 

 a matter of inference. The larger must either have resulted 

 from the incorporation of smaller ones, as globules of a liquid 

 would unite, or they must grow by addition to the surface. 

 The various appearances which they assumed, especially 

 those of the dumb-bell forms, seemed to be best accounted 

 for on the first hypothesis ; and as certain lenticular calcare- 

 ous bodies occurring in the scales of fishes, similar to the glo- 

 bules of carbonate found in the incipient stage of shell- growth, 

 had been described as undergoing a process of complete fusion 

 or incorporation, I adopted this hypothesis in respect to the 

 artificial products, as appearing to me to be the right one. 

 However, Dr. Gladstone, on examining some specimens which 

 I showed to him, considered that these globules were produced 

 according to the super-position theory, and Mr. Warrington 

 and Mr. Brooke, who saw them afterwards, were of the same 

 opinion. As I had great confidence in their opinions on this 

 subject, and as my only wish was to know the truth, and, 

 moreover, as I considered, in experiments so completely phy- 

 sical and chemical, and admitting so easily of being brought 

 within the reach of direct observation, certainty upon this 

 point was attainable, and no doubt need remain respecting 

 it, I proceeded to perform the series of experiments above 

 detailed, which I will now briefly apply in explanation of 

 the manner in which the calcareous globules acquire an 

 increase of size, according to the super-position hypothesis. 

 Though these experiments, so far as this point goes, may not 

 show anything new, yet they will have the advantage of 

 removing all doubt as to the manner in which the analogous 



