(1686) means that the ‘ little animal ’ only draws nourishment from the egg , when still in the egg , or whether he also has in mind the nourishment from the yolk during the first time in the life of the free - living animal .However this may be , he believes that the yolk of the egg only serves as food for the young animal , which , ( he thinks ) has its origin exclusively in the spermatozoon .te konnen halen .