232 Rhodora [DECEMBER 
Пех laevigata (Pursh) Gray. 
Ilex glabra (L.) Gray. 
Pyrus arbutifolia var. atropurpurea (Britton) Rob. 
Vaccinium corymbosum L. 
Viburnum cassinoides L. 
Rhus Toxicodendron L. 
Kalmia angustifolia L. 
Lyonia ligustrina (L.) DC. 
Osmunda cinnamomea L. 
Aspidium Thelypteris (L.) Sw. 
Sphagnum medium var. purpurascens Warnst. 
Sphagnum flavicomans (Card.) Warnst. 
Sphagnum imbricatum var. cristatum f. fuscescens Warnst. 
In the marginal fosse at the head of the bog grow: 
Sphagnum imbricatum var. affine (R. & C.) Warnst. 
Sphagnum pulchricomum v. pulcherrimum f. sphaerocephalum 
Warnst. 
Onoclea sensibilis L. 
The chief interest of the foregoing lists will lie in the fact that the 
chlorine content of the bog water was determined at the boundaries 
of the zones, and at the point of each zone where its characteristic 
flora was best developed. The few such data which have been pub- 
lished regarding littoral floras refer, for the most part, not to marshes 
or bogs but to the strand, where the conditions of plant growth are 
very different. The amount of sea water which would have to be 
mixed with pure water in order to bring the chlorine content of any 
given sample up to the value found by analysis was calculated on the 
basis of a chlorine content of 1.82% for sea water. ‘The samples were 
collected along the longitudinal axis of the bog, from holes made by 
pushing a post into the peat to the desired depth. After the water in 
the holes had attained its level and had settled somewhat, a sample 
was taken from each with a pipette. Chlorine was determined by 
titration with tenth normal silver nitrate, using potassium chromate 
as an indicator. An obscure end point of the reaction due to the 
coffee color of the water was avoided by greatly diluting each sample 
and by making titrations by artificial light. It was not even necessary 
to filter the samples. In the following table of results, an asterisk 
