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gularly, partly bent and partly cleaving to one another. When the 

 staining is done without desiccation, these irregularities may be 

 due to the currents the colouring liquid produces in mingling with 

 the water wherein the algæ are lying. In the cilia-staining prépa- 

 rons the water surface produces the same disorder in receding, as 

 the water evaporates. In the microscope I have seen how the 

 water surface in this way is able to bend the much stronger brist- 

 les of Golenkinia radiata. It is therefore to be supposed that the 

 same may be the fact in this case. 



Another observation shows that the bristles are very easily 

 bent, but also that they have a certain elasticity. I observed some 

 Pecliastrum duplex with beautiful bristles at dark-ground illumina- 

 tion and found Rotifera swimming lively about among them. Now 

 and then they drew near the Pediastra, and then it appeared that 

 only the water current from their cilia was able to bend the brist- 

 les. But as soon as the water current ceased the bristles took up 

 their original positions. 



I can only say very little about the chemical nature of the 

 bristles. The ordinary microscopic reagents are as a rule of no 

 avail in this case, and to get some results there is in the main 

 only to try staining with several colouring matters. 



The investigations of this kind I have made are however done 

 without any definite design. When I still shall give some results it 

 is only because they perhaps may give a hint in the right way. 



I have added chlor-zinc-jodine to specimens of Pediastrum 

 simplex, whose bristles on the marginal cells were so developed 

 that they could be seen without special measures; the bristles 

 then grew invisible, and also the knobs on the cell processes. It 

 is very likely that these parts are swollen or simply dissolved. 



I have made other tests with Pediastrum duplex var. clathra- 

 tum from Esrom Sø. The staining substances are always used 

 dissolved in water. The bristles and the knob on the cell pro- 

 cesses gave always the same reactions. 



colouring agents 



results colouring agents 



results 



Potassium iodide-iodine 



Ruthenium red 



Gorallin 



Safranin 



Methyl violet 



Aniline blue + acetic acid 



Methyl violet + tannic acid 



■4- Methyl violet -j- acetic acid 

 -r- Ruthenium red -f tannic 



pale colour acid 



pale colour Eosin 



-~ Congo red 



deep colour Vesuvin 



deep colour Vesuvin -f tannic acid 



deep colour 

 pale colour 



deep colour 



