Boyal Microscopical Society. 207 



Treating these seriatim, I would say that egg-shell, although 

 composed of the salts of lime, is virtually an animal product, and 

 therefore to be excluded from the inorganic division. As to its 

 physiological place, it may take rank among component elementary 

 bodies, supposing there is such a group, either form part of an 

 embryological section, or come under a division accessory to the 

 generative organs of birds. Its most natural position is illustrating 

 the textural character and peculiarities of the enveloping masses of 

 the young of vertebrates, and therefore subsidiary to development 

 near to the ovum. 



As respects copr elites, these might either be looked upon as 

 examples of earthy substances or as pecuhar fossil forms. But if 

 we bear in mind that coprolites are preserved as microscopical 

 objects almost always to demonstrate the remnants of minute fossil 

 bony structure, reptilian or otherwise, then there is no difficulty in 

 seeing that their true position is amongst osseous structures, and 

 along with the section which agrees in the constituent bony 

 particles. 



Calculi might with equal justice be classed with chemical sub- 

 stances or 2)athological products, and when no special series of the 

 latter exist, the former would be quite suitable to their nature. As, 

 however, urinary deposits commonly form a subsection of the urino- 

 generative organs, calculi may with equal propriety be inserted 

 after them. 



Ought pearls to go along with shells or as examples of disease ? 

 This, again, depends somewhat upon the nature of the collection. 

 Strictly s^oeaking, pearls are but a morbid condition of the nacreous 

 material of shells, and hence are true examples of disease. They 

 therefore, according to principle, should be ranged among patholo- 

 gical textures. In a miscellaneous series, however, where pathology 

 forms either an unimportant factor or is not meant to be exemplified 

 at all, then pearls necessarily come under the heading MoUusca, or 

 shell ; and in a subseries either together or after the representative 

 genus to which the shell belongs. 



Insects in amber, as a rule, are kept not as typical of the struc- 

 ture of the amber itself, but as exemplifying a peculiar nidus 

 wherein an insect may become imbedded. I would incline therefore 

 to place such an object among the groups of insects. Here either 

 close to the genus which the insect represented, or in a separate 

 and subsidiary heading devoted to " Insects imbedded in foreign 

 substances," at the end of insect structure. 



Works of art belong to the division of " Miscellaneous objects ;" 

 micrometers to the subsidiary heading of same devoted to " Appa- 

 ratus, &c." Test-objects may either be kept along with apparatus, 

 or as I conceive quite as philosophically, with their affined group of 

 organisms when diatoms. 



VOL. VII. Q 



