Fasten, Parthenogenetic Data. 
73 
It might be well at this point, to briefly summarize the various 
means that have been employed in securing artificial parthenogen¬ 
esis. McClendon has grouped them as follows: 
a. Hypotonic solutions (distilled water, Schiicking). 
b. Nearly isotonic solutions, made by adding to sea water, or to 
distilled water the f ollowing substances: 
Acids (Delage, Fischer, Herbst, Lefevre, Loeb, Lyon, 
Neilson, Schiicking, Tennet). 
Alkalis (Delage, Loeb, Schiicking). 
Neutral salts (Delage, Lilli'e). 
c. Hypertonic solutions: 
Acids (Delage, Loeb). 
Alkalis (Delage, Loeb). 
Neutral salts (Bataillon, Bullot, Delage, Fischer, Hunter, 
Kostanecke, Lo'eb, Lyon, Mead, Scott, Treadwell, Wilson). 
Non electrolytes (Delage, Loeb). 
d. Mechanical shock (Delage, Fischer, Mathews, Scott). 
e. Thermal changes (Bataillon, Delage, Greeley, Lillie, Loeb, 
Schiicking). 
f. Electric changes (Delag^e, Schiicking). 
g. KCN or lack of oxygen (Loeb, Lyon, Mathews). 
h. Fat solvents (Loeb, Mathews). 
i. Alkaloids and glucisides (Hertwig, Loeb, Schiicking, Wassilieff) 
j. Blood sera (Bataillon, Loeb). 
k. Soap and bile salts followed by hypertonic solutions (Loeb). 
Let us now consider the question of heterogeneous crosses. 
Loeb crossed Echinoid eggs with Asterias sperm in a concentrated 
solution of sea water, and although the sperm entered the egg, it 
nevertheless was thrust out again during early development, seem¬ 
ing thus to contribute nothing to the developing embryo. But the 
thing of importance is that the mere contact between the egg and 
the sperm induced segmentation and the formation of the yolk 
membrane. 
Loeb also crossed Echinoids with Chlorostomen, and more 
recently, Hagerdoon, working in the same laboratory as Loeb, 
produced crosses between Strongylocentrotus eggs and Asterias 
sperm. 
Kupelweiser, Tennet, Godlewski, Baltzer and others, have 
carried on work along similar lines. 
