40 THREE KINGDOMS. 



with the egg, and continued through the various forms 

 of the caterpillar after his moultings, the cocoon and 

 chrysalis, to the perfect imago. 



So, with a plant, an interesting group would repre- 

 sent its growth from seed to plumule, and through the 

 succeeding daily forms to bud and flower and fruit, 

 and back again to seed. 



Another variety of group-collection shows the sev- 

 eral stages in the manufacture of common substances. 

 Beginning with the cotton-boll, you would have the 

 ginned cotton, the thread, and various kinds of fabrics 

 that are woven from it ; starting again with the stalk 

 and flower of flax, you would have the soft, inner, 

 fibrous bark, the linen thread, linen and paper made 

 therefrom, also the seeds, and linseed-oil pressed out 

 of them, the linseed meal obtained by grinding the 

 oil-cake left after the oil has been expressed, and the 

 various other valuable products that make flax so 

 necessary to our comfort. 



7. The last sort of museum that I will mention may 

 be called the Type-collection. This is a collection of 

 typical specimens chosen to illustrate the branches, 

 classes, genera, and other divisions into which objects 

 are classified. Following the popular system, there 

 might be in the Animal kingdom, a cat to represent 

 the vertebrates ; a lobster for the Articulates ; an 

 oyster for the Mollusks ; for the Radiates, a star-fish ; 

 and for the Protozoans, a sponge. Of course the 

 classification may be carried to any extent you choose ; 

 but you would need only a few type-specimens in each 

 division. 



These must be considered merely as illustrations of 

 the different kinds of museums that may be made. 

 They range from the unlimited ' Omnium gatherum,' 

 which, I fear is the most common, as well as the most 

 unsatisfactory, through all the degrees of limitation. 



