194 Hunting for Diatoms. 



and even thrive, quite well in perfectly fresh water. Mixed 

 with the Bacillaria, we find Nitzschia sigma, and other free 

 forms. 



The wooden piers running out into the river are brown 

 with a covering of Homceocladia sigmoidea, Pinnularia John- 

 sonii, and Navicula ellipsis. On another wooden breakwater 

 we find Pleurosigma scalprum and Navicula mutica. 



Leaving the immediate vicinity of the docks we come to a 

 maze of ditches, to which the salt-water has access during 

 spring tides, and these ditches are often very rich in Diato- 

 macese. Let us commence operations here by collecting this 

 brown covering from the mud. Here we have Pleurosigma 

 angulatum, Fasciola, Strigilis, Hippocampus, Nitzschia sigma, 

 and Surirella gemma. Such gatherings may afterwards be 

 entirely cleaned from the mud by covering the outside of the 

 bottle with black cloth, and letting it stand for some days in 

 the sun. The diatoms by this time will have worked them- 

 selves to the surface, and the thick brown layer will be found 

 quite free from impurities. This plan, if carefully carried out, 

 rarely fails. The brown floating scum must by no means be 

 neglected, for on bottling some we find we have secured a good 

 gathering of Pleurosigma Fasciola, macrum, and delicatulum, 

 with, perhaps, Navicula ambigua, and other good things. 



Proceeding to another ditch, we will take a dip from the 

 mass of brownish stuff which coats the weeds. Well, here 

 indeed is a capital haul, for we have Nitzschia bilobata, Brebis- 

 sonii, vivax, with Tryblionella gracilis, Navicula amphisbama, 

 Pinnularia peregrina, and Gyprinus. 



Further on we pull out some of the weeds which are covered 

 with brown furriness, and we have a gathering of Synedra 

 fidgens and Amphipleura Danica; while on the mud we obtain 

 a copious one of Stauroneis salina, Nitzschia dubia /3, with 

 Navicula minutula. 



But what can this brown hair-like mass be, growing para- 

 sitically on the reeds and floating pieces of stick ? On exami- 

 nation it will prove to be pure Melosira Borrerii, which we will 

 bottle up with great satisfaction. 



Further on we come to a large lagoon, and find therein 

 some plants very promising in appearance, and well worth 

 gathering. These yield us afterwards a fine mass of Amphi- 

 prora alata and paludosa, Pleurosigma Strigilis, Amphora salina, 

 with Surirella Brightwellii. 



Mind how you step over this boggy ground, with the ink- 

 black mud, smelling so unpleasantly of sulphuretted hydrogen. 

 In spite of the smell, we shall probably get something to 

 reward us. Collect carefully the brown covering from the mud, 

 and you may find Naviculc, elegans, tumcn*, Nitzschia dubia, 



