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April 27'rH. 



MICROSCOPICAL MEETING. — MR. W. H. SMITH 

 ON "STARCH." 



In introducing the starches as a subject for microscopical 

 examination, he craved the indulgence of those who were well 

 acquainted with such objects, while he assumed, in accordance 

 with the wish of some members of the Society, that the meeting 

 consisted of persons ignorant of the subject. Starch was generally a 

 more or less glistening white powder, consisting of colourless 

 transparent granules of various shapes and sizes, usually distinct and 

 separate, but sometimes united together, forming compound granules. 

 Schleiden also claimed to have discovered it in an amorphous con- 

 dition, in the berk of Jamaica sarsaparilla, the seeds of cardaviotiium 

 minus, and the stem of carex- arenaria ; but other observers thought 

 that this had not been clearly demonstrated. The occurrence of 

 starch in plants was so universal that its presence was once thought to 

 be sufficient evidence to determine whether a body should be con- 

 sidered to belong to the animal or vegetable kingdom, until it was 

 shown that a body isomeric with starch could be found in certain 

 animals. It appeared to be of the same value to a plant that fat was 

 to an animal, or, in other words, it was a store of nourishment laid up 

 for future use ; hence it was found most abundantly in those plants, 

 and parts of plants, which were likely to require a large amount of 

 nourishment in a short time. Thus many plants accumulated starch 

 in their roots to an enormous extent before flowering, in order that 

 they might have support during that important period of their 

 existence. Carrots, turnips, and radishes were familiar e.xamples of 

 this kind of plant, whose roots were most fit for use just before flower- 

 ing, when every cell was gorged with starch granules, but were woody 

 and useless when the plant had run to seed and the granules, having 

 served to support it during its inflorescence, had disappeared. 



Starch was composed of carbon, united with the elements of 

 water, and although all starch had the same chemical composition, yet 

 every variety was more or less contaminated with some of the peculiar 

 secretions of the plant from which it was derived, and hence the 

 superior value of certain starches over others as articles of food. It 

 would unite with an alkali such as potash, forming a soluble salt, and 



