2S2 



THE GUIDE TO NATURE 



YAID 

 THE LENS 



One Diatom. 



BY I.. KUiXA C. ROHRABACIIER, SEATTLE, 

 WASH. 



We of the Northwest, never_ weary 

 of praising our glorious mountains and 

 their glacial systems; our beautiful 

 lakes, our majestic rivers; our unpar- 

 alleled forests, our strange and mag- 

 nificent fauna ; and our wonderful and 

 varied flora. We all know that it is 

 the naturalist's paradise. But we do 

 not so often hear, that it is also, an 

 unequaled treasure store of beauty for 

 the microscopist. 



Some of you, may have seen, during 

 your seashore visits, a young-great- 

 bearded gentleman in his eighties, 

 slowly walking along the beach. If 

 your eyes continued to follow him, you 

 probably saw him stoop to pick up a 

 piece of dried kelp, which had been 

 thrown up by the tide. Then he exam- 

 ined it with his magnifying glass. The 

 glass might have revealed an incrusta- 

 tion of tiny shells, which the unaided 

 eye could not discover. Attractive as 

 these are, and they are as beautiful as 

 larger shells gathered with such care, 

 they are not what he is searching 

 for, and the specimen is thrown 

 aside. Another one is examined. This 

 pleases better. What the glass reveals 

 is a finer incrustation than the other — 

 of very minute discs. These disc are 

 the siliceous skeletons of a species of 

 algae, of the order Diatomaceae, and 

 known to diatomists as Arachnoidiscus. 

 This is what our naturalist was search- 

 ing for. He will take this bit of kelp 

 to his laboratory, and through a long 

 and patient process, he will separate 

 the discs from the kelp, and by boiling 

 them in acids, will remove all vege- 



table, or other foreign matter. Then 

 he will place a tiny bit of the cleaned 

 diatoms under his compound micro- 

 scope, and if he finds a number of com- 

 plete, unbroken specimens, he will feel 

 amply repaid for all his trouble. 



May I try to describe this one form 

 of beauty which so abounds in Puget 

 Sound, and which our friend was look- 

 ing for so diligently? I use the word 

 "try" advisedly, for no verbal descrip- 

 tion could convey an adequate idea of 

 the exquisite, dainty, fairy-like beauty, 

 which, when we walk on the beach, we 

 thoughtlessly tread under foot, in count- 

 less millions. 



In searching for some figure of com- 

 parision, two come to my mind. First, 

 a cut-glass, flat plate. Not that it is 

 like any cut-glass plate that we have 

 ever seen, but because it is glass, it is 

 a disc, and it is ornamented with a pat- 

 tern, that looks as if it might have been 

 cut with the most perfect instruments, 

 and by the most conscientiously pre- 

 cise operator. 



The other figure is the web of the 

 wheel spider, threaded with the night 

 mist, and glowing in the morning sun, 

 with a thousand prismatic hues. This 

 latter figure is so true to its appear- 

 ance, it has given the diatom its gen- 

 eric name, arachnoidiscus. 



Were the diatom as etherial, and so 

 easily destroyed as the spider web, I 

 should not need to use my first figure, 

 the cut-glass plate. But Diatomaceae 

 are composed of pure silica, or, in other 

 words, glass, without the manufactur- 

 er's adulterations, and untold numbers, 

 in periods to long to read, endure in 

 perfect form, through geologic ages. 

 Therefore I will begin my description 

 with the imagined plate. 



