143 BOTANICAL GAZETTE. 



The characteristic odor given off in decay is aptly described as a 

 pig-pen odor. 



"Looking to the future, one may assert that no absolute remedy 

 can be proposed in case of the ponds already affected. They should 

 be cleared of weeds and substances in which \\~\t ISlostocs may lodge; 

 and, where it is possible to regulate the height of the water, it should 

 not be allowed to fall rapidly in the hot weatlier. Large and deep 

 bodies of water are less likely to be affected than small and shallow 

 bodies, and gravelly bottoms are better than muddy. The escape of 

 steam or hi it water should never be turned into ditches or streams con 

 necting directly with water supplies When such is the case, there is a 

 most luxuriant growth of species of the N'ostoc family, and the water be- 

 comes very foul." 



'Tn one respect, the fears nf the public may be set at rest. The 

 theory that certam diseases, as fevers, are produced by germs of some 

 low forms of plant-life, whether true or not, has no bearing on tne 

 present case. On the one hand, althougii we know that the species 

 described in the present article do cause the disagreeable pig-pen 

 odor, and do render the water at times unfit to drink, we know, on 

 the other hand, that they do not cause the specific diseases whose 

 origin is considered to be explained by the germ theory. The germs, 

 so called, are all species of bacteria, distinct from the iV^y/'tr family and 

 much smaller." 



"From a botanical point of view, the floating Nostocs ?lxq very 

 interesting ; but it is usually difficult to get good material for >.tudy 

 unless one is on the spot. The species of Atialuena are especially 

 prone to break up and decompose when sent by express, and the 

 various preservative fluids are of little use. To determine the species 

 one should have the spores and heterocysts in position. The best 

 way of preparing specimens is, by means of a pipette, to drop some of 

 the water containing the plants upon a piece of mica or glass, and 

 let it dry. The specmiens can then be sent any distance ; and, on 

 re-moistening, the plants swell up so that they can be well studied. 

 If they do not at once recover their form, a little ammonia or pot- 

 ash may be added. Information about the winter condition of the 

 vegetation is very much wanted; and especially do we need an accu: 

 rate chemical knowledge of their relation to the water in which tliey 

 grow." 



Destruction of Obnoxious Insects nv Means of Fungoid 

 Growths. By Prof. A. N. Prentiss. — This j^amphlet is devoted to the 

 detailing of experiments to test the proposition that certain obnoxious 

 insects can be destroyed by the application of the Yeast Fungus. The 

 result seems to be that yeast cannot be depended upon to rid our house 

 plants of the insects that commonly infest them. Of cnurse Prof. Pren- 

 tiss does not claim that his experiments decide the whole general ques- 

 tion, for yeast may be efficient in the destruction of other obnoxious 

 insects, or some other fungus may be used as a remedy where yeast 

 will not act. 



