mr. 34.] TO JOHN TORREY. 329 
have put the case in my introductory — and myself 
think of concocting a joint article, though my time 
will prevent me feom working out some of the subsidi- 
ary points just now. 
I assure you I am quite well and hearty, just in 
capital working mood. As to the lectures, I must 
work hard all the way through, but do not feel any 
misgivings. My house is hot enough, I assure you ; 
no trouble on that score. As to spontaneous genera- 
tion, the experiment of Schultz! is nearly or quite a 
st, and goes against it. Love to all. 
Bees yours, A. Gray. 
The next letter contains the first allusion to Isaac 
Sprague, so long associated with Dr. Gray as illustra- 
tor of his works. Isaac Sprague was born in Hing- 
ham in 1811. He early showed a faculty for observa- 
tion, and a gift for painting birds and flowers from 
nature. His talent was discovered, and he was invited 
by Audubon in 1848 to join his expedition to Mis- 
souri, and to assist in making drawings and sketches. 
President, then Professor, Felton, having met him in 
Hingham, and knowing Dr. Gray was looking for 
some one for his scientific drawings, recommended 
Mr. Sprague, and he began with the illustrations for 
the Lowell lectures and the new edition of the “ Bo- 
tanical Text-Book.” Dr. Gray was delighted with his 
gift for beauty, his accuracy, his quick appreciation 
of structure and his skill in making dissections. Mr. 
Sprague was from that time the chief, and mostly 
only, illustrator for his books, both educational and 
purely scientific. 
1 Carl H. Schultz-Schultzenstein, 1798-1871; professor of physi- 
ology in the University of Berlin. Wrote voluminously upon Cyclosis 
and the Vessels of the Latex, ete.’ 
