250 SPENCER FULLERTON BAIRD 
correspondence which it has not been practicable to print 
here, on account of necessary limitations of space. But 
the portions given, beside illustrating the traits of writers, 
then or since more or less eminent, will indicate the general 
character of the work carried on by Baird, the appeals 
made to him by correspondents, and something of the 
status of science at the time. A few of Baird’s own 
letters help materially. 
The following letter to Joseph Leidy! relates to the 
memoir on the microscopic fauna in living animals which 
was on the way to be published in the Smithsonian Con- 
tributions to Knowledge; and to papers on fossil verte- 
brates, especially from the West, a line in which Dr. 
Leidy afterward became so eminent: 
Spencer F. Baird to Joseph Leidy. 
Smrrusonian InstituTIOoN, WasuincTon City, Nov. 18, 1850. 
Dear Lewy, 
A rule was sometime since established by the Institution, 
that no plates should be authorized before the accompanying mss. 
was completed. This was in view of the fact of there being some 
twenty or twenty-five plates now completed, without a single line 
of text being ready. This, of course, involves a considerable loss in 
the unproductive investment of capital. Can you give any opinion 
as to the time when you will be ready to print. Where do you have 
the plates executed, how many do you require and when, and how 
soon after completion must they be paid for. 
I am glad to hear that you still persevere in your industrious 
1 Joseph Leidy, M.D., born in Philadelphia, Sept. 9, 1823; died 
April 30, 1891. One of the most distinguished naturalists of America, 
contributing largely to scientific literature on many branches of 
science. 
