Book Exchange. 23 



in its turn may feed upon the whiting, and that on the sprat, 

 and the sprat upon copepods, while the copepods feed upon peri- 

 dinians and diatoms. All such chains of food matters from the 

 sea seem to bring one through the copepods to the diatoms, 

 which may be regarded as the ultimate producers of food in the 

 ocean. So our living food from the waters of the globe may be 

 said to be the diatoms and other microscopic organisms as much 

 as the fishes. Naturally, if supplies of food from these "water 

 pastures" are to be utilized and increased in any intelligent way, 

 there is nothing for it but to carry out investigations of the 

 plankton in our fresh waters on a scale and with a thoroughness 

 that has never yet been attempted. 



BOOK EXCHANGE. 



The following list of books on fungi, myxomycetes and 

 lichens, bound and in good condition, is offered for sale. The 

 prices named include postage. 



DeBary. Morphologic und Physiologic der Pilze, Flech- 



ten und Myxomyceten. Leipzig, 1866 $1 .25 



— — ■ — ■ — Veigleichende Morphologic und Biologic der 

 Pilze, Mycetozoen und Bacterien. Leipzig, 

 1884 2.50 



Comparative Morphology and Biology of 



Fungi, Mycetozoa and Bacteria 4. 50 



Zopf. Die Pilze. Breslau, 1890 3 . 00 



Die Pilzthiere odei Schleimpilze. Breslau, 



1885 1.50 



Massee. Monograph of the Myxogastres. London, 1892 4.50 



Lister. Monograph of the Mycetozoa. London, 1894. . . 3.50 



Rostafinski. Sluzowce (Mycetozoa). Paris, 1875 and 



1876 9.00 



Soiauer. Handbuch der Pflanzenkrankheiten. Berlin, 



1874 2.00 



Plowright. Monograph of the British Uredineae and 



Ustilagineae. London, 1889 2.5Q 



