In her ‘Economic History and Economic Theory: Innis’s Insights’¹, Irene (Biss) Spry writes of a time when she was working closely with Innis:

His [Innis’s] work on the pulp and paper industry never reached publication as a book but appeared as an article in The Encyclopedia of Canada (1937, vol. 5, 176-85). The conclusion of this article makes it clear that this study was leading him into his later work on communications. (107)

Her reference is to the following concluding remarks to Innis’s Encyclopedia of Canada article, ‘Pulp-and-Paper Industry’:

The demand for newsprint has been closely dependent on advertising activity and on the efficiency of publishing houses in securing increased circulation. Wars have been important in increasing the consumption of newsprint and in increasing the efficiency of the printing press in securing increased speed. The radio tends to be complementary and competitive, and demands for economy have led to the narrowing of the margin of newspapers, to standardization of size to 20″ (8 columns of 12 ems), and to the emergence of smaller-size papers such as the tabloid. Expansion of press services and of advertising agencies has accompanied the marked improvements in communication and in the distribution of newspapers. The metropolitan press has steadily encroached on the papers of smaller centres, forcing amalgamation or abandonment. Compulsory education and the decline of illiteracy have been basic factors in the development of the industry. The power of the press [has been] increased by effective organization and expansion of large units (Hearst and Howard Scripps in the United States; Southam and Sifton in Canada)… (184)

Spry’s point seems to be that Innis here broaches factors in social history — war, education, entertainment, media — in addition to his usual concentration on more purely economic factors (treated, indeed, earlier in this same encyclopedia entry) like the availability of raw materials, access to water transportation, labour costs and financing.  And just as he had long been driven to investigate the complex inter-relations of the latter in his staple studies, so, Spry could see, would he now be drawn to understand the interconnections of the former in somewhat analogous fashion.

The result would be his communication studies where the new staple, apparently drawing on Eric Havelock’s work on the Greeks, was to be information storage over space and time. (For further consideration of this crucial period in Innis’ career, 1935-1937, see here.)