Sept.,1 Micro-Fauna, Botanic Gardens Lake, Melbourne. 79 



1918 J ' * 



ONE YEAR'S COLLECTING MICRO-FAUNA, BOTANIC 

 GARDENS LAKE, MELBOURNE. 



By J. Shephard, J. Searle, and J. Stickland. 



This investigation was undertaken as a result of a discussion 

 by the members of the council of the Microscopical Society of 

 Victoria. It was intended that members generally should take 

 part in it, but this was not found practicable ; but the three 

 members deputed to manage the scheme persevered, and suc- 

 sceeded in making periodical visits for a whole year. 



The visits were made mostly between the hours of one and 

 three in the afternoon, and approximately fortnightly. Stick 

 nets were used, but the chief instrument was the tow-net, of 

 the " Kofoid " pattern. 



The boat on the lake was made available by the courtesy 

 of the Director of the Gardens, Mr. Cronin, and the attendant 

 concerned materially helped by his willingness to meet the 

 wishes of the workers. As the plankton was the chief aim of 

 the work, on each occasion the net was towed by the boat 

 along open water of different portions of the lake, care being 

 taken to observe nearly the same track on each visit. The 

 resulting gatherings were brought away in jars in living con- 

 dition, preservatives not being used. The towing was mostly 

 done near the surface, but occasionally in the deeper parts of 

 the lake vertical hauls were made, which gave at times very 

 interesting results. Visits were also paid to the shady parts, 

 and differences in the plankton between them and the open 

 parts were found to occur. Collection from the shore by means 

 of the hand net were made. Mr. Stickland largely devoted 

 his efforts in this direction, the other members paying more 

 attention to the gatherings from the lake by means of the boat 

 and tow net. 



The lake has been formed from what was originally a swamp 

 covered with tea-tree, some of which may still be seen growing 

 near the eastern arm of the lake. Part of the scheme for the 

 prevention of floods in the lower reaches of the Yarra was the 

 straightening of the channel of the river. During the course 

 of this work a bend in the river bordering the Gardens was cut 

 off, and when the new boundaries were made this piece of water 

 was enclosed in the Gardens, and made part of the lake, which 

 now covers an area of several acres. The easterly extremity 

 is shallow, being only three or four feet in depth ; but the 

 western end, being part of the old river, is considerably deeper, 

 being in places over twenty feet deep. There is a very dense 

 growth of weed, which keeps the Gardens staff well employed 

 in keeping it within reasonable bounds. The interesting plant 

 Vallisneria is the most plentiful. The lake is supplied with 



