REPORT OF NATIONAL MUSEUM, 1921. 79 
persons connected with the Department of Agriculture have borrowed 
from the National Herbarium 44 lots of plants, aggregating 1,293 
specimens. 
DISTRIBUTION AND EXCHANGE OF SPECIMENS, 
Duplicates distributed to schools, colleges, and institutions aggre- 
gated 2,925 specimens, of which 1,242 were in 8 sets of mollusks, 
regularly prepared for this purpose, and two sets of 91 fishes each 
similarly prepared. 
A collection of about 500 glass eels, averaging in length 57 mm» 
was collected for and presented to Dr. Johannes Schmidt, of the 
Carlsberg Laboratorium, Copenhagen, Denmark, to assist him in his 
studies of the development of the eel. Of the alcoholic specimens of 
the 17-year cicada, collected for the use of colleges and similar 
institutions, as mentioned in last year’s report, one lot of 100 speci- 
mens was distributed this year. 
Exchanges to the number of 12,530 specimens were arranged, 11,926 
being botanical. Of the 604 zoological secimens, the most important 
exchange consisted of 149 bird skins, which were sent to the Museum 
of the University of Michigan; the remainder were disposed of by 
the divisions of mammals, birds, reptiles, fishes, marine invertebrates, 
and mollusks in small lots as exchanges with various institutions and 
individuals. The largest exchanges of plants were sent to the New 
York Botanical Garden, British Museum of National History, Mr. J. 
Theriot, Le Havre, France, Gray Herbarium of Harvard University, 
Field Museums of Natural History, California Academy of Sciences, 
and the College de Longueuil, Quebec. The others, made up of sets 
of less than 500 specimens, were exchanged with 53 different insti- 
tutions and individuals. 
TOTAL NUMBER OF SPECIMENS IN DEPARTMENT OF BIOLOGY, INCLUDING NUMBER OF DUPLICATE 
SPECIMENS. 
As explained in previous reports, the numbers given below can 
only be approximately correct. It would manifestly be impossible 
to count the specimens individually. The figures presented are based 
upon previous estimates, the numbers received during the year being 
added, and the specimens disposed of by gifts and exchange, or other- 
wise expended, being deducted. It should be noted that this census 
does not include the collections of mammals and birds in the custody 
of the Biological Survey. 
Duplicates have not been segregated in several of the divisions 
for various reasons, but more particularly because a large amount of 
material has yet to be worked over monographically, so as to make 
it safe to deplete the series. The figures furnished in last year’s re- 
port for the duplicates of fishes contained not only the number of 
duplicates actually segregated but also a rough estimate as to the 
71305°—21 6 
