BBCREATIVE. SCIENCE. 



85 



WHAT IS A DIATOM P 



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Some ten years ago (liow time does run on !— 

 it seems but as yesterday), a young man on 

 a visit to tlie Professor of Natural History 

 in th.e new Queen's College, then the most 

 recent attraction of " the beautiful city of 

 Cork," found himself unexpectedly' alone 

 amongst strangers. By a mysterious decree 

 of Providence his friend had been taken 

 alarmingly ill the night before, was then and 

 for weeks afterwards invisible to all but his 

 doctor and two amiable and accomplished 

 daughters. What was to be done? Hap- 

 pily, a work on the Diatomacese had been 

 projected, the illustrations to which had been 

 confided to his care; and, to begin upon, 

 four slips of glass had been given him, la- 

 belled " Aberdeen," " Premnay Peat," " Can- 

 tire," and " Loch Mourne," names now " fa- 

 miliar as household words " to the initiated 

 in these mysteries. On the central third of 

 each of these slips, protected by a square of 

 very thin glass, was to all appearance a little 

 fine white dust covered with gum ; the par- 

 tides composing which dust, when held up to 

 a bright light, flashed like rubies, diamonds, 

 emeralds — a perfect coruscation of fairy 

 gems. 



And these were DiatomacecB ? Our young 

 microscopist, like some of those who now in- 

 quire of him, had scarcely heard the word 

 before. To while away the time he now sat 

 down to these four slides, with the concise 

 yet comprehensive instructions from his 

 great captain, to " draw all he saw before 

 him :" not bad training thib for eye, and hand, 

 and patience, as all who know what a fine 

 mounting of similar gatherings, where forms 

 difiering in age by centuries may be included, 

 is like. Slowly then during these weeks did 

 the work progress, and such was the fascina- 

 tion produced by their beauty in the artist's 

 mind, that day after day he sat at them ; 



night after night, the morning sun frequently 

 rising ere his couch was sought for brief ne- 

 cessary repose. An occasional stroll through 

 the fine scenery in the immediate neighbour- 

 hood, for health and recreation, afforded also 

 an abundance of living specimens of many of ■ 

 the forms whose skeletons he was engaged in 

 depicting, in addition to Desmidiese and other 

 objects of interest to the microscopist. The 

 Vice-President of the College, with the warm- 

 heartedness of a true Irishman, took com- 

 passion on the stranger, asking him in occa- 

 sionally to tea and a social evening, when by 

 other i^rofessors and visitors the question was 

 repeatedly put with which our chapter is 

 headed, "What is a Diatom?" To these 

 learned fellows, versed in aU the circle of 

 the sciences, the reply that "the siliceous 

 portion of the infusoria of Ehrenberg, called 

 by him ' Bacillaria,' had more recently had 

 this name given to them," served its imme- 

 diate purpose of conveying ideas on the sub- 

 ject sufficient for most of the questioners. To 

 add to the interest of the evening, the micro- 

 scope was on two or three occasions brought 

 in, and some of the most elegant forms ex- 

 hibited. 



But some of the readers of Eeceeative 

 Science may be none the wiser for such a 

 definition, which, it must be admitted, is after 

 all vague enough ; since, translated into sim- 

 pler language, it means little more than that 

 the name had been changed of some minute 

 moving bodies found by the microscope in 

 water, together with such animalcules as our 

 forefathers used to breed from infusions of 

 chopped hay, tea-leaves, and so on, and hence 

 called "Infusoria." The most prominent 

 distinguishing feature in the portion in ques- 

 tion being the possession of shields or shells 

 that resist the action of fire and concentrated 

 acids, being formed of flint. 



