Hechtlinger, Adelaide. The Great Patent Medicine Era. New York City:  Grosset and Dunlap. 1970.

A highly recommended source of information on the very early history of patent medicines in America is: 

Griffenhagen, George B., and James Harvey Young.  Old English Patent Medicines in America. United States National Museum Bulletin 218, Contributions from the Museum of History and Technology, paper 10:  155-183 1959.

     DR. MORSE’S PILLS LIVE ON

Although the original Comstock enterprise has been dissolved and all of its undertakings in North America terminated, as has been related herein, Dr. Morse’s Indian Root Pills and Comstock’s Worm Tablets are still being manufactured and sold—­by the W.H.  Comstock Company Pty.  Ltd., in Australia.  This concern, originally a subsidiary of the Canadian company, is headed by the former branch manager for the Comstocks, who acquired the rights for Australia and the Orient following the dissolution of the Brockville company.  Distribution is also carried out from this source into New Zealand, Singapore, and Hong Kong.  Packaging and directions are now modern, the pills being described as “The Overnight Laxative with the Tonic Action,” but a reproduction of the old label and the facsimile signature of William Henry Comstock, Sr., are still being portrayed.  Thus, the Indian Root Pills have been manufactured continuously for at least 115 years and the Comstock business, through the original and successor firms, has survived for nearly 140 years.