FHKSII WAPKi; IJKK. 15 



There is no need to coii)[)are a tVe.-li ^•a)llple with this as the 

 quantity of life is fully up to the average. 



In this specimen, although the conditions otherwise were 

 the same as specimens 1 and 2, the addition of vegetation to the 

 water seems to have made all the diheience in the world. 



Specimen No. 4. 



Collected April, 11)02; examined Dec. 13th, 1904. 



This specimen was in a milk basin and stood on the o tftce 

 table two years and eight nn)nth3, a little water (town water) 

 being added each morning to add oxygen and supply the loss 

 by evaporation. The specimen wa^ put down a- follows; Some 

 sand and a few stone.-^ in the bottom; then the specimen water 

 was added, nearly tilling the basin; then some water grass from 

 the same brook, L do not know the variety, was planted in the 

 sand, as also some bunches of Dichelyma capellceum. Then on 

 tlie surface were set afloat some Salvinia naians, Riccia natans 

 and Riccia tiuitans. Of the contained life nothing is known ex- 

 cept that there was a large numl)er of snails of two varieties, 

 Planorbus deHectus and Lunnea culumella. Watching this 

 specimen with the naked eye i could follow the snails. To my 

 >ur[)rise they ditl not appear to touch the water grass nor float- 

 ing plants. 1 could not see if they fed on the Dichelyma or not, 

 but a softtiuh'y speciCs of algye formed on the sides of the basin 

 under water and they mowed swaths through that, so that you 

 could trace them in all directions. Some even came up out of 

 the water and died on the edge of the l)asin. 1 also noticed 

 cycles occurring in other aquatic life, probably cyprids or chy- 

 d(»ri, or both; it was impossible to tell with the naked eye. They 

 Would swarm in immense numbers for a week or so, and then 

 you would hardly see one. On the day of examination. Uec. 

 Ijih. 1904, the appearance was as follows; The water grass had 

 grown over the side of the basin and was hanging down one 

 and a half feet over the edge of the table. The Dichelyma was 

 growing fairly, but the Salvinia and both specimens of the Riccia 

 had entirely disappeared. The microscopic examination showed 

 the following:; 



