ZOOLOGY AND BOTANY, MICROSCOPY, ETC. G7 



Diatomaceous Dust on the Bearing- Sea Ice-floes.* — E. M. Kindle 

 describes his investigations of the diatomaceous dust found by him on 

 the ice-floes off the south-west coast of Nunivak Island in June 1908. 

 The ice cakes comprising the floes were more or less discoloured by dust 

 or dirt. Some of the dust was found to be of volcanic origin, and in 

 this, as well as in the other grey non-volcanic dust, were found consider- 

 able numbers of marine diatoms. A list of fifteen species is given, 

 found in samples collected about 30 miles north-west of Cape Roraanzof, 

 and named by Dr. Mann. Diatoms have not before been observed on 

 the Behring Sea ice, and the recorded occurrences of these organisms on 

 floating ice elsewhere are not numerous. Some have been recorded by 

 Nansen and Vanhoffen. The nearest locality to Behring Sea from 

 which diatoms have been found on floe ice is near Cape Wankererna, 

 west of Behring Strait about 200 miles. The author proceeds to compare 

 the list of species from the Behring Sea with those recorded by the 

 'Vega' and the ' Frarn,' and finds that the Behring Sea flora is related to 

 that" of the Pacific, and not at all to that of the Polar Sea. The fact 

 that the diatoms of Cape Wankerema, about 400 miles from Cape 

 Romanzoff, bear the closest resemblance to the diatoms of the east 

 coast of Greenland, and the almost complete unlikeness between the 

 Wankerema and Behring Sea floras, -affords convincing evidence that no 

 definite marine current connects the two areas which could carry the 

 Wankerema flora southward or the Behring Sea flora north-westward. 

 On the other hand, the close resemblance of the Behring Sea ice diatoms 

 to the Pacific flora, which is shown by more than nine species common 

 to the two, indicates a close relationship through marine currents with 

 the Pacific Ocean. Dall's conclusions regarding the movement of water 

 in the southern part of Behring Sea corresponds with the evidence of the 

 diatoms in this respect. The author quotes from Dall's report on the. 

 U.S. Coast and Geodetic Survey for 1880. 



Physiology of Diatoms. f — O. Rickter has continued his studies on 

 the physiology of diatoms, and has succeeded in cultivating a colourless 

 marine species, namely, Nitzchia putrida. He gives an account of his 

 methods. N. putrida is typically saprophytic, and assimilates leucine, 

 asparagin, pepton, and albumen ; and when suitable sources of carbon 

 are present, also the inorganically combined nitrogen of nitrates and 

 ammonium compounds. Negative auxauograms can be raised by the 

 help of substances of an acid reaction. In the course of generations 

 the normal power of movement becomes lost. The species appears to 

 be extraordinarily capable of variation. This paper is so full of in- 

 formation that it must be studied in the original. 



Halopteris scoparia and Sphacelaria radicans.J — C. Sauvageau has 

 described in previous papers the peculiar development of Cladostephus 

 vert ir Hiatus, and the manner in which the young plant passes through 

 stages resembling Sphacelaria and Halopteris before taking on the 

 characters of Cladostephus. He has also stated that there is a similar 



* Amer. Journ. Sci., xxviii. (1909) pp. 175-9 (1 fig.). 



t Denkschr.k. Akacl. Wiss. Wien, lxxxiv. (1909) pp. 656-772 (pis. and text-figs.). 



% Journ. de Bot., ser. 2, ii. (1909) 27 pp. 



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