19-i PROCEEDINGS OF THE ACADEMY OF [April, 



not reproduce itself without being fertilized, nor can the hen or 

 cock reproduce themselves without mutual union of their reproduc- 

 tive elements. In other words, this criterion makes no allowance 

 for the general occurrence of organisms which complement each 

 other in ensuring px-ocreation. It is doubtful whether any organism 

 can reproduce itself indefinitely without at least occasional interac- 

 tion with another organism ; in the Metazoa the dioecious condition 

 would appear to be the primitive one ; accordingly, the lowest organ- 

 isms at some period in their reproductive cycle, the highest organ- 

 isms at each period of reproduction, need cooperation with coinple- 

 meutal individuals in order to insure successful reproduction. 

 Whether the complemental individuals are structurally alike, as in 

 the Infusoria and hermaphroditic Mollusca, or whether they are struc- 

 turally dissimilar, as in most dioecious forms, it Avould still hold that 

 the single organism would not be capable by itself to reproduce 

 itself. And again, accidentally infertile organisms or normally 

 infertile organisms, such as the worker females of the Hymenoptera, 

 could on this definition not be classed as individuals since they are 

 unable to procreate themselves ; yet, no one would maintain that an 

 ox or a worker ant is not an individual.^ Therefore this criterion 

 of individuals, the ability by itself to reproduce itself, must be 

 changed to " ability, on interaction with complemental individuals, 

 to reproduce itself.'' But this definition will not enable us to 

 determine the individuals to be considered in phyletic classification, 

 as we shall proceed to show. 



There are found among organisms, as has been so frequently 

 reiterated, many degrees and kinds of individuals. For each more 

 complex organism must be decided what is the higher individual, 

 and what the individuals of lower grades. The ideas of corm, 

 stock, person, organ, intergrade, sometimes- for the same organism, 

 almost always when we compare complex organisms of different 

 kinds. Thus we may term ' ' colony ' ' or " corm ' ' the connected 

 individuals of the protozoan Glohigerina, a proliferating H3'droid 

 stalk, the unified bundles of spermatozoa of an Isopod Crustacean, 

 or a compoimd Tunicate. And yet how these several organizations 



'^ This objection to the definition is not, however, perfectly fair, since 

 ni classification we deal with normal and hot accidentally mutilated 

 organisms, and since a worker ant may in one sense be considered 

 embryonic, becanse its genital organs and ova do not attain a complete 

 development, bnt are arrested in their growth. 



