The Influence of Extraneous Factors 81 



buffer diluent by the inclusion of various additives such as gela- 

 tine (Knoop, 1941), glycine (Knoop and Krauss, 1944; Tyler and 

 Tanabe, 1952), sodium citrate (Willett and Salisbury, 1942; Salis- 

 bury, Knodt and Bratton, 1948), bicarbonate and glucose (Kamp- 

 schmidt, Mayer, Herman and Dickerson, 1951), dialysed yolk 

 (Tosic and Walton, \9A6a) and liquid whole egg (Dunn and Bratton, 

 1950); to counteract the danger from bacterial contamination, cer- 

 tain antibiotics are sometimes added such as penicillin, strepto- 

 mycin, polymixin, aureomycin or sulphonamide drugs. On this sub- 

 ject alone there is a vast number of publications of which only a 

 few can be quoted here (Knodt and Salisbury, 1946; Bay ley, Cobbs 

 and Barrett, 1950; Branton, James, Patrick and Newsom, 1951; 

 Foote and Bratton, 1949, 1950; Hennaux, Dimitropoulos and 

 Cordiez, 1947; Pursley and Herman, 1950; VanDemark, Salisbury 

 and Bratton, 1949; VanDemark, Bratton and Foote, 1950; Willett, 

 1950; Dunn, Bratton and Henderson, 1953). 



Some attempts were made a while ago to replace the egg-yolk 

 buffer diluent by a chemically more clearly defined, artificial 

 medium. Thus, Phillips and Spitzer (1946) developed the so-called 

 *L.G.B.-pabulum' which contained as essential ingredients 1-2% of 

 a lipid fraction (L), made up of lipositol (an inositol-containing 

 phospholipid), 0-6% glucose (G), phosphate buffer (B), pH 7-4 

 (0-2% KH2PO4 and 2% Na2HP04-12H20), with 0-2% galactose, 

 003% of sulphasuxidine or streptomycin, and lastly 3% gum acacia, 

 added to provide 'sufficient body to prevent the settling out of sperm 

 upon standing in storage'. Other substitutes for egg-yolk which 

 have been suggested at various times, include milk, glycerol, paraffin, 

 arachis oil and synthetic plasma-substitutes such as 'periston' 

 (Laplaud, Bruneel and Galland, 1951; Koch and Robillard, 1945; 

 Rostand, 1946, 1952; Asher and Kaemmerer, 1950; Thacker and 

 Almquist, 1953). 



It remains for future investigations to invent an ideal diluent. 

 Such a diluent would be expected to combine the following features, 

 isotonicity, efficient buffering capacity, nutrient value, antibacterial 

 potency, stabilizing action of a 'protective colloid', anti-oxidant 

 ability, and above all, good keeping quality in a ready-to-use form. 

 Furthermore, it should protect semen from the effects of sudden 

 changes of temperature and preserve its full fertilizing capacity for a 



