368 Experimental Zoology 



Quetelct found 133.5 males to 100 females; Bodio gives :- 



MALES 



Italy 131.1 



France 142.2 



Germany 128 3 



Austria . 132.1 



Hungary ........ 130.0 



Switzerland 135.0 \ to 100 females 



Belgium . 132.0 



Holland 127.1 



Sweden i35- 



Norway 124.6 



Denmark 132.0 



From these results it is clear that the proportion of male to 

 female embryos is distinctly in favor of the males. The mean- 

 ing of this is unknown. 



Monoecious Species, composed of Bisexual or Hermaphrodite 



Individuals 



Since the groups of animals with which we are most familiar, 

 the vertebrates, insects, and higher crustaceans, are composed 

 of individuals with separate sexes, we are apt to forget how often 

 in other groups the sexes, or more accurately the sex-cells, are 

 united in the same individual. In the following list some 

 of the groups are given in which hermaphrodite individuals 

 exist : 



Sponges, sexes separate or united. 



Coelenterates, sexes separate or united. 



Flatworms, sexes united, a few cases of separate sexes. 



Nemerteans, sexes rarely united. Separate sexes the rule. 



Nematodes, sexes separate as a rule, but united in some cases. 



Annelids, sexes united in earthworms, separate in marine worms (except 



Protodrilus). 



Crustacea, sexes separate, but united in some barnacles. 

 Mollusca, sexes separate in some, united in other groups. 

 Echinoderms, sexes separate, united in a few cases. 



Thus in the greater number of the great groups, hermaphro- 



