Eugenics and Genetics 
greater rate than other cells, particularly if obtained from a 
“genetically labile’? animal species such as hamster. 
Crick: If you are going to store germinal material for any 
length of time, it is absolutely essential to see whether there will 
be any deterioration, and this should be investigated as soon as 
possible. On theoretical grounds, many types of mutation 
would not happen at very low temperatures; others might. 
I don’t think it is fair to apply to sperm the arguments 
used for other cells, because the sperm head is packed in a 
particular way, and the sort of damage you might get in low- 
temperature storage of other cells might not necessarily occur in 
spermatozoa. 
Koprowski: Could the results of artificial insemination of 
animals with frozen semen be applied directly to man? 
Crick: If something works with animals one is more confi- 
dent, but not completely confident. But this should certainly be 
worked out extensively with animals. 
Pincus: Large numbers of bull calves have been born after 
artificial insemination from frozen semen and there has been 
no evidence of an increase in the mutation rate. However, if 
mutation to recessive lethals occurred, it would not show up in 
the first generation, and I do not know of many studies beyond 
the first generation. 
Hoagland: I might mention that we have worked with what 
was perhaps the first human sperm bank. In 1940 Pincus and 
I showed that if human sperm were dropped into liquid nitro- 
gen, they could then be revived if one warmed them up very 
quickly; 60 per cent of them were motile even when they had 
been kept for indefinite periods of time with dry ice. We could 
not vitrify and recover sperm of domestic animals to any 
significant extent. Human sperm are quite exceptional in this 
respect. Storage of animal sperm did not become practicable 
until Parkes and his group developed a method using glycerol 
as a protective substance in freezing. 
About this time I wrote a rather facetious article in the 
Scientific Monthly pointing out that women might have offspring 
by selected long-dead donors; they could perhaps choose the 
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