THE NAUTILUS. 29 
DR. JOHN A. RYDER. 
Dr. John Adam Ryder, Professor of Comparative Embryology at 
the University of Pennsylvania, and one of the most eminent em- 
bryologists and histologists in the world, died at his residence in 
Philadelphia, March 26, after a short illness, at the age of 43 years. 
The immediate cause of his demise was a complication of nervous 
troubles, which brought on gastric symptoms. Dr. Ryder was a 
very hard student, and his death was doubtless caused largely by 
over study. 
JOHN A. RYDER, PH. D. 
Dr. Ryder was born near Loudon, Franklin County, Pennsyl- 
vania, in 1852. He received a common school education and en- 
tered an academy, where his educational course was interrupted by 
financial reverses to his father. He then adopted his life work 
