FEESHWATER ALG.E. 191 



pieces of strong glass a couple of inches square, to each of wliich is 

 cemented with gold size or marine glue an indiarubber ring about one- 

 eighth of an inch thick. These, when piled on one another, and held 

 together by indiarubber rings, take up but little space. Lastly, for these 

 coarser plants nothing answers much better than to screw them up in 

 bits of strong paper and bring them home in a "wide-iuouthed bottle, tin 

 box, or even loose in the pocket. A specimen need, at any rate, never be 

 left behind for want of a more elaborate vasculum. 



The Desmidiacete require more care, and the gathering should be 

 transferred with as Kttle shaking as possible to one of the glass tubes 

 which should he filled with water. 



It is a useful plan, when out for a long walk, to number the speci- 

 m^ens, and note down their exact habitat in a pocket book. Some years 

 ago the writer returned from a five and twenty mile walk across the 

 Welsh Mountains, with some fifty "dips" of all sorts. Next day was 

 devoted to their examination, and in one tube, among a quantity of 

 common species, were found two frustules .of Docidiuni wdosum, a 

 Desmid hitherto recognised as exclusively an Amierican species, but 

 wliich has been since found, we beheve, by Mr. Archer, in Ireland. 

 Unfortunately, no such record as we suggest had been kept ; and, 

 although the writer started o£f next morning at daybreik, took exactly 

 his previous route, and searched sedulously till nightfall in eveiy tiny 

 pool in which he remembered dipping in his previous ramble, not a trace 

 of the new plant was found. 



The specimens being brought home, each should be transferred in 

 turn to a small saucer, or watch-glass, and poi-tious of it examined under 

 a convenient power, generally about half an inch. If any new species is 

 spotted, it shotild be set aside for motmting, duly labelled temporarily ; 

 but, if the gathering seem to contain nothing but old friends, it is a useful 

 plan to give it a parting squeeze between the fingers, and catch the 

 drippings in a watch-glass. Small Desmids and Diatoms, previously 

 entangled, are pressed out in this way, and new species often reward the 

 examination. The squeezed mass should not be thrown away till the 

 washings have been searched over. It often pays to repeat the process. 



A specimen should never be thrown away because it is a poor one, 

 or consists of one individual, where a dozen would be acceptable. The 

 rarest plants are naturally often met with singly. Once, in examining a 

 m.ass of very dirty stuff from a Welsh bog, the writer pounced in his first 

 dip on the rare Desmid, Micrasteria^ radiosa. Eashly concluding that 

 there were sure to be plenty more, he swilled back the contents of the 

 slide into the mess. But dip after dip, and washing after washing, were 

 examined in vain ; and, as the species was too rare to be hghtly lost, it 

 cost the work of two long nights to hunt over the entire mass, drop by 

 drop, till the individual plant, whose diameter was about l-140th of an 

 inch, was recovered. 



We say, therefore, nwunt a poor, specimen rather than none. If you find 

 a bitter you can throw it away, or give it to a friend, who will value it. 



