989 



plant in question, and hence he might be led to form an erroneous 

 conclusion as to the condition of the water. The observer, therefore, 

 who wishes to come at its real state, should make the tour of the 

 whole of the Serpentine. Considered in a sanitary point of view, Dr. 

 Hassall is of opinion that the plant, when actually introduced into 

 the system, as when swallowed in bathing, would not be productive 

 of effects injurious to health, and regards it as a test of impurity and 

 as an evidence of the very bad condition in which the water of the 

 Serpentine now undoubtedly is. Dr. Hassall concluded the commu- 

 nication by observing that the colouration of large pieces of water 

 by means of Confervae is by no means unfrequent, and cited as a re- 

 markable instance of it the Red Sea, which owes its name and colour 

 to the presence of a minute plant diffused through the water of 

 a blood-red colour. — G. E. D. 



Anacharis alsinastrum of Babington at Watford Locks. 

 By Thomas Kirk, Esq. 



In announcing the discovery of this plant at Watford Locks, I ex- 

 pressed an opinion, founded chiefly on the fact that it had only been 

 announced from artificial and extremely suspicious localities, of its 

 being an introduced plant. The subsequent announcement of its dis- 

 covery in natural localities in Nottinghamshire, Staffordshire, and 

 Berwickshire, having proved it a true native, I have thought a short 

 account of a summer visit to Watford Locks might not be unaccept- 

 able to those botanists who have had no opportunity of seeing 

 the plant in a living state. 



The Anacharis is abundant in all the reservoirs attached to the 

 Locks, the plant growing in such dense masses that it is with diffi- 

 culty good-sized single specimens can be detached, owing to its ex- 

 treme brittleness. Flowers were only procurable in those places 

 where the water was but slightly disturbed, and were most abundant 

 in the upper reservoir, the water of which is much less disturbed than 

 either of the others ; there they were in profusion, looking at a short 

 distance like threads of white silk which had been scattered over the 

 surface of the water. I, however, searched all the reservoirs in vain 

 for the least trace of female flowers ; and, I believe, none have yet 

 been found in this country. Many large, matted patches of the plant 

 occur in the canal itself, both above and below the Locks, but I could 



