JET. 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 from 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 l is nearly or quite a 

 test, and goes against it. Love to all. 



Ever 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- 

 hani 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 1843 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, etc. ' 



