23 



Whea it is desired to obtain a larger supply of microsoa 

 from the open sea, it is needful to use a naturalist's tow-net, which 

 is simply a bag of any fine textile material attached to a metal 

 ring. So bng as it will allow water to pass, the testu'e of the 

 material can hardly be too fine or close, when very minute life is 

 being sought. 



But a prolific source of embryonic and other stages of low 

 Hie is the slimy coze in the tortuous water courses of the marshy 

 areas bordering creeks and rivers. This soft unctuous substance 

 constitutes a very comfortable resting place for myriads of forms 

 which are at once small, curious, and beautiful. In sucb places 

 near the confluence of the Thames and the Medway, and pro bably 

 in all our rivers. Infusoria, Rhizopods, and Annelids, may be 

 found in all stages of development. 



As this marine mud has not received much attention in the 

 past, it is not surprising that everal forms, new to science, 

 have recently been found, some of which have been described, 

 while others still await investigation. 



But by far the most numerous of the minute objects 

 found in the salt marsh rills are Diatoms. These tint the mud 

 surface with pleasant shades of colour ranging from golden 

 yellow to dark brown : the intensity being in direct proportion 

 to the abundance of the little plants. Looking down into a 

 shallow rill, it is highly interesting to see silvery looking globules 

 of oxygen crntinually rising all along the field of view, thus 

 giving evidence that Diatoms in such places not only hide the 

 unlovely aspect of the mud but also purify it and the supertiuent 

 water. When the tide has ebbed sufficiently an enormous quantity 

 of Diatoms and other living microscopic objects can be 

 secured by lightly skimming off some of the coloured film from 

 the mud surface. On getting home with the semi-fluid mud it 

 is usual to put it into a clean jar and liquefy it still more with 

 sea water, and let it stand where it will be fully exposed to 

 light. In the course of a few hours mud and water separate, 

 and the Diatoms once more congregate in a thicker and there- 

 fore darker layer on the mud, as well as on the side of the jar 

 which happens to be the most brightly illuminated. They are 

 then easily accessible, and can be studied at convenience. 

 Various genera are peculiar to such localities, and are not often 

 found elsewhere. Of these, the most abundant, as well as the 

 the largest is Pleurosigma. P. anguJatum {^^ of an inch long 

 to ^\-^ of an inch wide) is a very prominent species, and is often 

 found in groups by itself. In the living state, this Diatom appears 



