On the Library and Archives Canada (LAC) website, I've found the Nominal Roll containing Private David Murison. Unfortunately; I'm having trouble figuring out how to cite a pdf'd document, which is part of a collection of similar documents. The organization of the LAC site adds so substantially to the confusion that I'm not sure where to start. Just getting to the document is a "labour of love."
So; if you can, I could use a bit of a nudge in the correct direction...
The document is contained in a volume/box called, "Canadian Expeditionary Force - 49th to 60th Battalions - Nominal Roll of Officers, Non-Commissioned Officers and Men", which is a collection of several similar documents under LAC reference RG9-II-B-3, Volume/box number: 79. After a lot of trial and error, I finally determined that this collection can be accessed via, http://www.bac-lac.gc.ca/eng/CollectionSearch/Pages/record.aspx?app=FonAndCol&IdNumber=2006095
The document is a PDF of the paper copy that the site refers to as, "50th Canadian Infantry Battalion - embarkation 1915-10-27 - arrival 1915-11-04 (item 2)".
The pages of interest are pp. 1 (title page showing embarkation information) & 15 (showing entry for Private David Murison, #434298), taken on strength 15 January 1915 at Calgary.
And... When I finally did get to the actual document, I found the direct link was simply, http://data2.archives.ca/e/e444/e011089541.pdf (However; I know from past experience not to use that.)