Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2018

Dilutive Shares Which Could Exist Pursuant to Exercise of Outstanding Stock Instruments and Which were not Included in Calculation

Dilutive shares which could exist pursuant to the exercise of outstanding stock instruments and which were not included in the calculation because their affect would have been anti-dilutive are as follows:

	September 30, 2018 (shares)		September 30, 2017 (shares)
Warrants to purchase shares of common stock		10,697,026		12,249,590
Options to purchase shares of common stock		3,764,648		4,656,888
Shares of common stock issuable upon conversion of preferred stock		4,308,115		4,312,282
		18,769,789		21,218,760