niMTisn 



water, and after the superfluous liquid is allowed to drain 

 away, squeezed over the wide mouth of the tube or 

 bottle. The sediment that settles to the bottom of the 

 bottle usually contains Desmids, more or less numerous. 



/ 



One may always depend upon finding sonic Desmids in 

 material squeezed from permanently submerged fiplitnj- 

 num. 



Round the rigid leaves of I.W/rx and Lol><'li there is 

 often quite a thin gelatinous coating of a yellowish- 

 brown colour. This can be removed from the water 

 by getting the leaves between the fingers, with the 

 hand palm upwards, and then gently drawing the 

 hand upwards through the water. This method of 

 collection requires much patience and some practice, as 

 it is exceedingly difficult to raise in the open hand, 

 lio-ht, flocculent, o-elatinous material a distance of 



O 7 O 



about two feet through the Avater. Most of the finest 

 and purest material we have ever examined has been 

 collected in this way. 



All the larger Algas should be carefully collected, 

 because it is amongst these that some of the most 

 interesting Desmids are found. Similarly, the home 

 of many characteristic Desmids is amongst the mosses 

 and filamentous Alga3 which occur on dripping rocks. 



In the sheltered corners of some lakes there is often 

 a growth of Phragmites or 8cirj>/ix la matrix, and scrap- 

 ings of the older stems of these plants frequently yield 

 o-ood results. A net of coarse muslin or a coarse 



O 



copper strainer will be found to be very useful for 

 passing amongst submerged plants. For the examina- 

 tion of large ponds and lakes the use of a boat is of 

 great service and often indispensable. 



To collect the plankton-material from large lakes, 

 tow -nets are necessary. These nets are conical in 

 shape and constructed of miller's silk ; they are six or 

 eight inches wide at the opening, and fourteen to twenty 

 inches in length. The open end should be sewn on to 

 coarse sail-cloth, the latter being doubled and fastened 

 to a stout copper ring, and then three equidistant holes 



