[235] Beyerinck 1890.

[236] Artari 1902.

[237] [See p. 56.]

[238] Artari 1902.

[239] Treboux 1912.

[240] Chodat 1913.

[241] See Paulson and Hastings 1920.

[242] Keeble 1910.

[243] Reinke 1872.

[244] Dufrenoy 1918.