212 



KNOWLEDGE 



[Seftbmbbb, 1902. 



The low sjiiidy shore or flat muddy estuary, thou>^li 

 yielfling their pcculiiir species, are not by coraparisoii to 

 be considered. 



Mr. Geiirj,'e Murray in his introduction to the Study of 

 Seaweeds "fives the foilowinf,' information regarding (he 

 three colours of seaweeds : — "As a general rule the inshore 

 seaweeds near high-water mark are green iu (■olour like 

 land vegetation, and lower down between tide-marks thert^ 

 is a belt of olive forms siieltering red plants beneath them. 

 Where rocks overhang the bottom and in small pools these 

 red forms also occur at this level. At extreme low-water 

 mark and beycmd it are found the brown tangles sheltering 

 red forms again, while at the lowest depths of plant life in 

 the sea the red forms occur without shelter." 



The collector should provide himself with some small 

 tin boxes, such as are used by botanists, and these should 

 contain little oiled silk bags in which to place the speci- 

 mens; or an ordinary water-proof sponge bag hung on the 

 arm is a good vecej)tacle. A strong short chisel, firmly 

 iixcd at the end of a stout stick of alpenstock pattern, and 

 having at the other end a small net, is also necessary, the 

 fonner to dislodge pieces of weed from shells or rocks 

 otherwise beyond reach, the latter to catch floating 

 specimens. The stick will also be found useful as a 

 sujiport when on the rocks, for it is here when the tide is 

 at its farthest that he will have to search for his treasures. 



They will be found in the little pools aliout the rocks, 

 some growing on pebbles, others on shells, while some will 

 spring from the rock itself. After a storm is a particularly 

 propitious time for search to be made along the shore, for 

 tufts will frequently be torn from inaccessible regions, 

 while at other times a variety of specimens will be found 

 thrown uj) by the waves and stranded on the beach. The 

 waste of a fisherman's haul should also be examined. 



Specimens thus secured may be preserved in sea water 

 without deterioration, and in particular Delesseria alata, 

 Polysiphonia, Callithamnion, and Bryopsis ulva thrive well 

 in aquaria. The collected material should be placed in 

 transparent receptacles, such as glass jars, so that they 

 may be readily examined. 



Marine Algae make particularly good dried specimens, 

 and the method to be adopted for preserving them in this 

 manner is as follows : — They should be thoroughly washed, 

 lirst in salt water and finally in fresh water. The speci- 

 men should then be placed iu a shallow dish, and a sheet 

 of drawing paper gently placed beneath it as it floats in 

 the water; the paper may then be gradually drawn ujj and 

 the specimen thus lifted in its spread out condition. The 

 specimens so arranged should then be carefully covered 

 with drying paper, and botanical pressure boards or a board 

 with a considerable weight upon it should be used, the 

 papers being changed frequently until the sj^ecimens are 

 quite dry. 



It has to be remembered that the dried specimens rarely 

 retain the beautiful colours of the living plant. In many 

 cases the chlorophyll granules are embedded in the 

 pigments of various colours, and are sometimes almost 

 indiscernible. 



On the death of the plant these colouring matters 

 frequently undergo a change, and much of the beauty of 

 the specimen is thereby lost. 



The process of mounting marine AlgK for the microscope 

 is <]uitf simple, and with care and practice the work can 

 be done with great facility. The modus operandi is as 

 follows : —The weed should be well washed in the same 

 manner as for dry mounting, and the portion which shows 

 the most interesting structure — fructification, etc., if 

 possible- should then be removed with a shar|i i>air of 

 scissors and transferred with the forceps to a 3 by 1" slip 

 It is then carefully drained of superfluous water by a 



eloih placed close to it to absorb the moisture. It must 

 not, however, be allowed to get jterfectly dry. 



The best medium for mounting is Deane's gelatine, 

 wliicli is reduced to a fluid condition by placing (he bottle 

 containing it in a Ijath of hot water The slips should 

 now be very gently warmed, and a small <|uantity of the 

 medium transferred, by means of a warm glass rod, from 

 the bottle to the slip. The amount of medium should 

 b(' just sufficient in quantitj' for a ^" circle to cover 

 comfortablv. 



The cover-glass having been warmed in a spirit lamp 

 flame on the side which is to be away from the specimen, 

 is gradually tilted down on the specimen and the slide set 

 aside to cool, the exuded gelatine being removed when 

 hard by means of a knife and a ]>iece of soft sponge 

 dipped in warm water, nnd used as rapidly as posfible. 

 It may subsequently be finished with any of the varnish 

 cements. 



For travelling purposes the majority of (he specimens 

 may be safely carried in wide-mouthed bottles with w^ell- 

 fitting corks, and many species will keep tlius for months 

 or even years, but some delicate specimens, such as 

 Callithamnion corymbosum, Sphondylothamnion niulti- 

 fidiura, and Mesogloea, are best kept in glycerine until 

 required for mounting, the glycerine being washed ofi 

 beforehand. 



The corallines are red sea-weeds whose tissues are 

 hardened by chloride of lime. Before mounting they must 

 be cleared by washing in a weak solution of hydrochloric 

 acid, or, better still, by using Perenyi's decalcif3ing fluid. 



Fbesh-watee Alg^. — The majority of specimens 

 when collected require to be placed and carried in water, 

 necessitating that the collector shall take with him some 

 well-corked wide-mouthed bottles. 



One of the most generally useful arrangements for 

 gathering specimens is one of the collecting sticks sold by 

 opticians, which is provided with net, bottle, cutting hook, 

 drags, etc. These various fittings enable all lands to be 

 taken — the free-swimming Vofvox, the floating Spirogyra, 

 and the Desmids and Diatoms, which may be found in the 

 mud at the bottom. 



It will often be found convenient to concentrate 

 gatherings, which may be done by stretching a piece of 

 fine muslin across a bottle, superfluous water being drained 

 away and the specimens retained, and all placed in one 

 instead of several bottles. 



To preserve fresh-water Algae, it will be found advan- 

 tageous to shield them from direct light by tying a stiff piece 

 of green paper round the vessel in which they are contained. 



In mounting these specimens f or niicrosi'opical examina- 

 tion, the same jjrocesses may generally be adopted as for 

 marine Algas, excepting that of course the salt-water 

 washing is omitted, but the delicate structure of many of 

 the species necessitates their being mounted in a cell. The 

 medium that has proved most generally satisfactory is 

 Deane's gelatine, thinned with camphor water, or with 

 distilled water containing a trace of pure carbolic acid. The 

 gelatine keeps the medium from evaporation, and is easier to 

 use than an ordinary fluid. Some species, such as Entero- 

 morpha, may be mounted in the Deane's medium without 

 dilution. Spirogyra and Volvox are better mounted with 

 Deane's gelatine 50 jier cent., and thinning material for 

 the other half. Spirogyra may also be mounted in dilute 

 alcohol, and this shows up the nucleus, although the colour 

 suffers. 



Specimens mounted in fluid or semi-fluid media should 

 be sealed up immediately in order to prevent evaporation. 

 This is best done with a ring of Hollis's glue, and care 

 shoulil bp tnken to finish with a sufficiency of varnish to 

 prevent all chance of evaporation at later periods. 



