ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 745 



basins in November 1908 and February 1909 ; but no greening of tbe 

 oysters had taken place up to the beginning of April, when the basins 

 were partially emptied and most of the oysters removed, and the water 

 supply was cut off. But ten days later tne basin began to have a blue 

 tinge, and the oysters became an intense green, the diatoms having 

 undergone rapid multiplication. To make cause and effect clear, 

 further experiments are required : but it is already evident that the fol- 

 lowing conditions favour the development of the diatoms : (1) stagna- 

 tion of the water in the basins ; (2) low level of the water ; (3) tempera- 

 ture of water varying between 13° and 21 C. ; (4) a salinity of about the 

 density 1016 to 1017 ; (5) neglect generally. 



Marine Diatom which stores up Manganese,* — J. Peklo describes 

 a species of Gocconm growing on a quantity of Cladophora fracta var. 

 marina ; it was coated by a deposit of manganese, and formed a 

 brownish-black mass on the shore of one of the Dalmatian Islands. 

 He describes the various methods he employed for analysis, and the 

 corresponding results. The deposit seems to be derived from manganese 

 carbonate taken up by the plant. 



Fossil Diatoms at Furnas.f — F. A. Chaves writes an interesting 

 account of two strata of fossil diatoms in the island of St. Michael, one 

 of the Azores. They were both discovered by himself some years ago, 

 and, having been prevented from completing his researches on them, 

 he now publishes his notes. After discussing various geological strata 

 in the Azores, the author gives lists of the fossil diatoms found in the 

 Bargado and the Tarnbores beds. The first contains 38 species, the 

 second 56. Of these 27 are common to both. A list of the living 

 diatoms known from the Azores follows, numbering 126, and a com- 

 parison of these with the fossils of Bargado and Tarnbores shows that 

 27 and :'>7 species respectively are common to the fossil and living species. 

 Then follows a list of 91 species from the fossil deposits of Auvergne, 

 and comparison between these and the Azores beds shows that 23 and 

 30 species only are common respectively to the two regions. It is, there- 

 fore, impossible to establish any analogy between the two regions other 

 than their formation in fresh-water. The author then gives his views 

 on the mode of formation of the strata at Bargado, with a photograph 

 of the spot where the fossil diatoms are found. 



Morphology of the Base of Cladophora.ij: — F. Brand has made a 

 study of this subject, and describes and figures the base of Cladophora 

 glomerata. By the term " base " he understands the lowest part of the 

 main filament, together with the basal organ of attachment. Up to the 

 present time stress has always been laid on the absence of primary 

 rhizoids in the hydrophilous JEgagropilse and C. fracta, but the varying 

 form of the base of stationary species has never been described. The 

 author finds that the basal shoot of the germinating plantlet divides 

 at a very early stage into two branches, or, in certain cases, into more 



* Bot. Zeitsch., lix. (1909) pp. 289-98 (1 pi,). 



t Bull. Soc. Portugaise Sci. Nat., ii. (1909) pp. 231-55. 



% Ber. Deutsch. Bot. Gesell., xxvii. (1909) pp. 292-300 (figs, in text). 



