14 
members. The arrangement of the conchological collection, 
which is now equal, in scientific value, to any other in the 
world, has been completed; a volunteer labor of seven years’ 
duration by members of the Conchological Section of the 
Academy. 
The classification of this collection required the fixing in 
appropriate trays 76,479 specimens, and the writing of 24,285, 
labels, in order to fully display 14,161 species. In the process 
of verifying these, and eliminating duplicates, several thousand 
names were transferred from the catalogues to the synonymy; 
thus reducing to this extent the number of species previously 
supposed to exist. Several families and genera are so complete 
that no known representative of them is wanting. To assist the 
Chicago Academy of Science in acquiring collections in this 
department to replace those destroyed in the great conflagration, 
863 species determined and appropriately labelled, have been 
sent to it; and 100 species in addition are now ready -to be 
transmitted. Besides these there are nearly or about 5000 lots 
of duplicates, estimated at 25,000 specimens in all. 
The Microscopical and Biological Section of the Academy 
has been active. Some of its work may be mentioned. Dr. 
James Tyson presented the results of his microscopic study of 
blood and epithelium ; Dr. Albert Fricke reported his investi¬ 
gation of the horse epidemic of 1872 ; Mr. D. S. Holman ex¬ 
hibited his peculiar microscopic slides which are valuable im¬ 
provements, and recently he has devised a method of demon¬ 
strating to an audience the circulation of the blood in animals, 
and of the sap in plants, which will be satisfactory to teachers 
and lecturers; and Dr. J. Gr. Hunt made interesting and valu¬ 
able communications; on his discovery that the common truffle 
grows in the neighborhood of Philadelphia; on the use of 
haematoxylon in the preparation of stainings of both vegetable 
and animal tissues, and he demonstrated that a curious turbidity 
of the water in the reservoir of the Camden Water Works, 
which had puzzled different scientists, was due to the growth 
of the Trichormus thompsoni. He exhibited specimens of 
this microscopic plant, and pointed out a method of preventing 
