Frequency - Word Form
 195 first
 184 than
 173 cause
 169 both
 165 does
 164 animal
 164 do
 163 its
 162 eggs
 162 reason
 158 uterus
 150 like
 149 been
 148 body
 148 there
 145 an
 144 no
 143 embryo
 140 young
 135 others
 129 come
 125 egg
 124 now
 123 heat
 122 any
 119 kind
 118 comes
 117 many
 115 birds
 113 another
 113 each
 109 much
 106 should
 105 again
 105 principle
 104 produce
 104 say
 104 secretion
 104 time
 103 case
 102 formed