abstracts: fisheries and plant pathology 241 



sediment, but immediately begin to fuse into conglomerate masses, 

 which in turn unite and metamorphose until the sponge is eventually 

 restored. 



The experiments were made chiefly with Microciona prolifera, which 

 it was shown can be perfectly regenerated by this method of growth from 

 dissociated cells. Lissodendoryx carolinensis is less hardy, and it proved 

 difficult to dissociate the cells in healthy condition, but the behavior 

 of the tissue was the same as in Microciona. In Stylotella heliophila 

 the behavior of the tissue was slow and feeble as compared with Micro- 

 ciona, but the plasmodial masses were formed. In neither of the latter 

 two species, however, did the plasmodial masses metamorphose. 



Intermingling of the red tissue of Microciona with the bright green 

 of Lissodendoryx failed to produce fusion of the different species, as did 

 also the intermingling of tissue of Microciona and Stylotella. 



E.M.Smith. 



FISHERIES. — Effects of explosive sounds, such as those produced by 

 motor boats and gunshots, upon fishes. G. H. Parker. Bureau of 

 Fisheries Document No. 752. Pp. 9. October, 1911. 



To the human ear, when the listener is under water, the noise of motor 

 boats and the sound of gunshots, even at very close range, are very slight. 

 Testing fishes in enclosures with the same kinds of sounds the following 

 conclusions were reached: 



The sounds produced by motoi boats are extremely faint under water 

 and have little influence on the movements and feeding of fishes. Such 

 influence as they do have is temporary and very much restricted in local 

 extent. 



Single explosive sounds, like the report of a gun, may startle fish and 

 cause them to cease feeding, but these responses are also temporary 

 and local. 



Altho most sounds are repellent to fish, some may serve as lures to 

 particular species. E. M. Smith. 



PLANT PATHOLOGY.— The rusts of grains in the United States. 

 E. M. Freeman and Edward C. Johnson, Bureau of Plant Indus- 

 try, Bulletin 216. Pp. 87, pis. 1. 1911. 

 This paper embodies results of a detailed study of the grain rusts with 

 regard to distribution, relationships, physiology, and life history. Par- 

 ticular attention is directed to "biologic forms" of rusts, vitality of 

 successive uredo generations, wintering of the uredo generation, clima- 

 tology in relation to rust epidemics, and methods of breeding grains for 

 rust resistance. Some of the more important conclusions derived follow : 



