Aquatic ILitt 



135 



reveals these organs in operation. You 

 seem to look through a window at a deli- 

 cate clockwork, so transparent is the skin 

 of most of them. Manifold are their 

 shapes. Free swimmers have balancers 

 and other attachments assisting them in 

 floating and swimming. Most of the ses- 

 sile species construct protective casings 

 of foreign matter (Melicerta), or exude 

 jelly-like covering (Floscularia) . Others 

 are merely attached by a pedicel ending 

 in a sucking disc. Melicerta ringens, as 

 an example of a case-builder, possesses 

 a so-called "pill-organ," which is an open 

 sac fringed with cilia, placed immediately 

 below the mouth. This sac catches stray 

 little grainlets and turns them into pills 

 with the aid of mucus or slime. These 

 are then carried out and deposited along 

 the upper edge of the case, the entire 

 case being built from such pellets. 



Rotifers can withstand drying up — des- 

 sication — for some time, being then blown 

 about with the dust and thus carried far 

 and wide. When they again reach water 

 they flourish as before. This state of 

 anabiosis (lifelessness) is a well-known 

 phenomenon shown by many microorgan- 

 isms which, after two hundred years of 

 observation, still is not well explained. 

 Rotifers can remain in this inert condi- 

 tion for months and years with impunity. 

 Possibly they exude a jelly-like substance 

 which permits the retention of the modi- 

 cum of moisture which carries the ani- 

 mals through this period of drought. 



Life is very elastic and adaptable to 

 many contradictory phases, and even then 

 may triumph over death. Perhaps even 

 these minute "wheel bearers" may pos- 

 sess organs within their bodies whose sig- 

 nificance is so far unknown to us. The 

 illustration shows three species very much 



magnified. 



■#- 



A little attention every day keeps "ole 

 man death" away — from your fishes. 



Red-colored Water 



A few months ago one of the most pro- 

 ductive of the "daphne ponds" of the 

 aquarists of Philadelphia assumed the 

 color of red ink, and thereafter was dub- 

 bed the "ink pond." A brief investiga- 

 tion has failed to disclose the cause of 

 the condition. Barring the effects of an 

 occasional oiling by the local health au- 

 thorities, Daphnia (apparently one of the 

 many varieties of D. pulex) and rotifers 

 do not find the water inimical, while the 

 protozoan fauna is normal. The coloring 

 seems to be due to a soluble inorganic dye 

 which did not form a precipitate after 

 standing for a week in a graduate. 



The last report on the fisheries of New 

 South Wales makes the following com- 

 ments on red-colored waters in Australia : 



"In April several patches of red-col- 

 ored water were observed in different 

 parts of Middle Harbour, particularly in 

 Long Bay, Sailor Bay, and Sugarloaf 

 Bay. 



"Samples of the water were forwarded 

 to the Government Analyst, who chemi- 

 cally examined them, and found a heavy 

 proportion of suspended solids, chiefly 

 organic, and reported that it was possible 

 that the amount of oxygen dissolved in 

 the water was much reduced, but no sub- 

 stance injurious to fish life was traced. 



"Many years ago a similar phenome- 

 non occurred in the waters of some of 

 the more secluded bays of Sydney Har- 

 bour, notably in Blackwattle Bay. The 

 red color appeared in patches, which 

 gradually spread over the whole of the 

 waters. The matter was investigated at 

 the time, and the color found to be due 

 to protozoa, more particularly to a then 

 undescribed species of Peredinium. 



"The red coloration in Middle Harbour 

 disappeared naturally in the course of a 

 few weeks, without having any apparent 

 ill effects on fish or oyster life." 



Peridiniuin is a genus of flagellate pro- 

 tozoans also represented in the United 

 States. The species are quite small, 

 measuring from forty to sixty twenty-five 

 thousandths of an inch, and in color may 

 be green, yellow or brown. — Editor. 



