HA.RDWICKE'S SCIENCE-GOSSIP 



145 



HOW TO CUT SECTIONS OF ALG.fi 



By Mrs. MERRIFIELD, BRIGHTON. 



HAVE been 

 asked bow to cut 

 sections of algae, 

 and thinking tbat 

 some of your 

 readers may also 

 like to know bow 

 to perform tins 

 ' simple operation, 

 so indispensable to the stu- 

 dents of algae, I beg to send 

 the following communication 

 on the subject for insertion 

 in Science-Gossip. 



Materials. 1. Some 

 pieces of clear glass, about 

 3 inches by 1 or 1§ inch. 



2. A piece of thin, smooth 

 cork, about 2 inches diameter: 

 a good smooth bung will do. 



3. A piece of white card- 

 board (not glazed), about 2 inches by 1£ or 2 

 inches, with square corners. 



4. Two pointed instruments for arranging the 

 sections, &c. Convenient tools for this purpose are 

 made by inserting the heads of large needles into 

 the pith of pieces of elder, about 4 inches long, and 

 as thick as a lead pencil. When dry, the elder 

 twigs form good handles. 



5. A pair of tine-pointed scissors. 



G. A cutting instrument. Dr. Harvey recom- 

 mended for this purpose a razor set in a firm 

 handle, so as not to close ; or, a child's gum-lancet, 

 also set in a firm handle. The razor may do for 

 cutting sections of laminaria, &c, but I found it 

 very clumsy for small weeds. I obtained from a 

 cutler, to whom I explained what I wanted, a very 

 thin knife-blade, about the size of a penknife, set 

 in a firm handle, with a sheath to protect it when 

 not in use. This answers the purpose very well. 

 Cost Is. 6d. 



7. A 



No. 



few 

 139. 



1 Naturalist's pockets " of paper, for 



putting away small scraps of algae, which you wish 

 to preserve. 



8. A good drawing-pencil, and india-rubber. 



9. Some pieces of white paper to make enlarged 

 drawings of sections, small branches, fruit, &c. 



10. Some oblong pieces of clear talc, on which 

 specimens of fruit and small branchlets may be 

 preserved for after- examination by the microscope. 



11. A small bottle with glass stopper, containing 

 dilute muriatic acid. 



12. The stick of a lucifer match. 



13. A moderate-sized hair pencil ; some pieces 

 of rag. 



14. A box to hold all these objects. 



15. A glass of clean water. 



To make a cross-section of an alga :— If you 

 can get fresh plants from which to cut sections, so 

 much the better. They must not, however, be too 

 wet, for in this case the pressure of the knife 

 would crush them, so that you could not cut a 

 clean section, or understand the structure. If the 

 plant to be examined be wet, cut off a convenient 

 piece, and lay it in a cloth, when it will soon 

 be dry enough for the purpose. Select for cutting 

 a portion which is a fair sample of the plant, bear- 

 ing in mind that the lower parts of the stem are 

 often of denser structure than the upper. For this 

 reason it is sometimes necessary to make cuttings 

 from both upper and lower branches across the 

 frond. A piece of the plant about the fourth of 

 an inch in length will be enough. If the plant 

 from which you are cutting be too dry, the sections 

 will scatter away and be lost. To avoid this, wet 

 the fragment, and let it dry sufficiently in a cloth. 

 When it is ready, place the cardboard on the cork, 

 and the piece of alga on the cardboard, the surface 

 of which is yielding, and not so likely to blunt the 

 knife as the harder surfaces of wood or metal, and 

 being white, you can see the sections as they are cut. 

 Bring forward the forefinger of the left hand, lay 

 your nail on the alga, so that you can only just see 

 the edge of it beyond your nail. Then take the 



