BIOLOGY. 281 



Mann, Albert, Washington, District of Columbia. Continuation of investiga- 

 tions and preparations for publication of results of work on Diatomacece. 

 (For previous report see Year Books Nos. 18-21.) 



Diatom investigation this year has progressed more satisfactorily than in 

 previous years, as adequate help for handling the ever-increasing quantity of 

 material sent to the laboratory has been secured. Mr. Paul S. Conger and 

 Mr. L. B. Copeland have joined the laboratory force and have taken up this 

 line of investigation with the intention of making it their permanent vocation. 



As it has become more generally known that reports on diatom deposits, 

 fossil or recent, were available, there has been a steady increase in the number 

 of requests made for analysis. During the year 17 consignments of fossil 

 diatom material (amounting to 116 samples), and 8 of recent material 

 (amounting to 231 samples) have been accepted, studied, and reports thereon 

 made. Several of the fossil class had to do with commercial problems of 

 immediate economic value. 



Two investigations deserve special mention here. Professor A. N. Win- 

 chell, of the University of Wisconsin, sent in three samples of dust from the 

 upper atmosphere, brought down by snow-storms at or near Madison, two 

 of which contained diatoms. Atmosphere diatoms were known to exist, but 

 these samples contained several species not hitherto found in such material. 

 The other remarkable case was that of a sub-fossil diatom flora found in an 

 ancient bald-cypress swamp, uncovered during building excavations at De 

 Sales Street and Connecticut Avenue in Washington, D. C, in November 1922, 

 Studies of the swamp material were made by several scientists interested in 

 the various organisms discovered in it, as well as a general survey of the 

 geology of the deposit. Papers were prepared, and were read at a meeting 

 held under the auspices of several of the Washington scientific societies. 

 The diatom paper proved to be especially serviceable in determining the 

 character, climate conditions, and approximate age of the swamp, because 

 of the larger number of species found than of those of the other groups, and 

 their much better preservation. 78 species were obtained, only a meager per- 

 centage of which are now living in this locality or in bald-cypress swamps 

 existing in this part of the country; but a large proportion of them were 

 seen to be identical with those composing the Pleistocene fossil diatom beds 

 at Montgomery and Cunningham, Alabama, and a sub-fossil bed at Crane 

 Pond, Massachusetts. The correspondences with the latter were over 82 per 

 cent. 



The work at Woods Hole, Massachusetts, is now in its seventh consecutive 

 year and is therefore nearing the time when a sufficiently long series of obser- 

 vations will afford trustworthy data on the seasonal variation of species and 

 the relative abundance of diatoms in that vicinity in relation to the food sup- 

 lAy of marine fishes, clams, and oysters. Six weeks were spent there this 

 summer, and ample collections were made for carrying on this fine of study. 



During the year the preparation of the manuscript on the Philippine Islands 

 diatoms has been finished; the study of the diatoms of the Canadian Arctic 

 expedition has been about completed, and all the material of the Austra- 

 lasian Antartic expedition has been prepared for examination and more than 

 half of it examined. 



Two years ago a trip of three months was made to the Pacific Coast, the 

 main object of which was to start diatom research at favorable localities that 



