COLLECTING 157 



lectors should study carefully each special locality 

 above all, on exposed rocky shores before risking 

 themselves too far out at ebb tide. 



On the collecting-ground the best specimens avail- 

 able should be always selected, and, if the fruit can be 

 detected, fertile specimens should be carried home in 

 preference to sterile ones. Specimens covered with 

 parasites should only be gathered for the sake of the 

 latter. When botanizing on algologically poor and 

 rarely visited coasts or reefs, it is best to take whatever 

 can be found, in order that we may get an insight into 

 the nature of the flora ; but, as a rule, only specimens 

 in a good state of preservation should be taken. 



To preserve algae there are different methods, accord- 

 ing to their final destination, either for research in the 

 laboratory or for the herbarium. For laboratory work 

 they must be put in various fluids, best studied in 

 papers enumerated at the end of the book. For each 

 special investigation there are almost always special 

 methods of preservation. For general investigation, 

 algae may be put at once in alcohol of 70 per cent., or in 

 a solution of formalin (i to 2 c.c. formalin in 99 to 98 c.c. 

 fresh water*) . In alcohol algae will shrink a little, and 

 lose their colour ; in formalin they do not shrink, and 

 keep their colour a long time if kept in the dark. But, in 

 the long-run, a solution of formalin affects the tissues 

 slightly. One per cent, chrome alum in distilled 

 water, carefully filtered through sand, is, according to 

 Guignard and Lotsy, an aqueous solution that does 

 very well for Myxophyceae, Chlorophyceae and Rhodo- 

 phyceae ; Phaeophyceae do better in formalin. 



For the herbarium algae can be either roughly dried, 



* Sea water can also be used for making up solutions, but 

 rusts all steel instruments used on the material afterwards in 

 a most annoying way. 



