ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 681 



Biology of Diatoms.* — Matteo Lanzi makes some interesting bio- 

 logical observations on Diatornaceas. He points out the use of these 

 plants in purifying fresh- and salt-water, in the composition of the 

 so-called guano, and in the nutrition of animals. At the end of his 

 remarks the author gives two lists of Diatoms ; the first enumerates 

 thirty-nine species found in the stomach and intestines of a fresh-water 

 fish caught near Domodossola, and the second is a list of fifty-eight 

 species found in a fish from the Mediterranean. 



Micrasterias.j — J. A. Cushman records ten species and five varieties 

 of this genus from south-eastern Massachusetts, of which three varieties 

 are new. He finds the genus is almost wholly confined to ponds and 

 lakes, but few occurring in streams. In ponds and lakes there are many 

 species present, and usually an abundance of specimens. Critical notes 

 are appended to the species names. 



Development of Cocconema.j— C. Turner has found developmental 

 stages of C. Cistula, which he describes and figures. The earliest stage 

 seen by him consists of a minute spore, which is brown in colour and 

 contains four dark brown nuclei. The spore increases in size, and four 

 diatoms are formed within the protoplasm, the frustules being gradually 

 secreted and deposited around the four nuclei. The spore may contain 

 one, two or three young diatoms, instead of four. 



Diatoms of Koh Chang.§ — E. Oestrup publishes a list of 274 

 species of marine diatoms contained in 74 samples of material 

 ■collected by the Danish Expedition to Siam in 1899-1900. The 

 genera which characterise the material as a whole are Cocconeis and 

 Mastogloia. Fresh-water species occur singly, especially in samples 

 from mangrove swamps. Plankton forms are rare, and occur only as 

 fragments. Taken as a whole, the material is rich both in individuals 

 and in species, but it is uniform. The marine diatoms of Siam have a 

 tropical character, but do not occupy a peculiar position among the 

 East-Indian marine diatoms, such as might have been anticipated. 



Dutch Plankton. ||— H. C. Redeke publishes the result of his investi- 

 gations during the years 1897-1901, made on the plankton of the 

 Zwanewater, a small lake in the North Sea dunes near Callantsoog. On 

 account of the shallowness of the water, the plankton corresponds with 

 that of the littoral zone of a larger lake. In the number of forms and 

 •of individuals, the zooplankton exceeds the phytoplankton. 



North Sea Plankton.^" — H. C. Redeke and P. J. van Breemen give 

 a list of phyto- and zoo-plankton collected in the southern waters of the 

 North Sea between 52° and 51° N. lat., 0° and 4° E. long. Tripos- 

 plankton occurred principally in the north of the region examined, being 



* Atti Pont. Accad. Nuov. Lincei, lvi. (1903) pp. 129-41. 



f Bull. Torrey Bot. Club, xxxi. (1904) pp. 393-7 (3 figs, in text). 



X Rep. and Trans. Manchester Micr. Sue, 1903, pp. 88-91 (1 pi.). 



§ Botanisk. Tidsskrift., xxvi. (1904) pp. 115-61 (2 pis.). 



|| De erven Loosjes. Haarlem, 1903, 5 pis. 



If Tijdsch. Nederl. Dierk. Vereeng. (2) viii. (1903) pp. 118-47. 



