No. 605] NUCLEUS AND CYTOPLASM 



287 



If this delmition of ''determined" is accepted, two 

 kinds of continuity in organisms are immediately differ- 

 entiated. The first sort may he called snhstantial con- 

 tinuity. It is the carrying over from one generation to 

 the next of autonomous organizations of protoplasm in a 

 manner analogous to the carrying of the bacilli of certain 

 diseases {e. g., syphilis) in the germ cell. Here the germ 

 cell is a passive vehicle. The character is present, not 

 determined; and its changes from fertilized egg to adult 

 are mere proliferations. If hereditary characters were 

 to he so viewed, and the view carried to its logical con- 

 clusion, the result would he something very like an "em- 

 boitement" theory, which facts of development have 

 proved to he untenable. Substantial continuity i< hence 

 only a concomitant rather than a part or a method of 

 heredity. 



The >econ:l type of continuity may be called "omrtir'' 

 continuity, and characters which are genetically con- 

 tinuous are tliose whicli sliow a new coming into brinu: 

 with every generation. Tlicy are .IcvcIoihmI <nn //•. aii<l 

 their resemblance to honiolou-ons <'1iai'act(M's in th(^ pre- 

 ceding generation is due to Iheii' (leNelopiiient not tVotn 

 tJwse characters hut froin lioiiioloa'ons tieterurninnls. 

 Characters of this type ai-e ti'uly deterniined and all 

 hereditary characters are redncilile to this type wlu'ther 

 they are exhibited in egg, sperm, embryo oi' adult. 



It is now ])ossible and desirable to define the expres- 

 sions "inheritance through, the cytophism" and ''inher- 

 itance through the chromosomes." The first ]iroiH;'rly 

 means that the locus of the determiner- or re])re<enta- 

 tlves of a character is llie cyto]>lasni, and since it is the 

 egg alone which C(-»ntnins any sio-niiicnnt aiiionnt of cN to- 

 plasm, the expre-Hon UMinlly mean- the pre-cii.-e of t ■ .-e 

 determiners in the egg cytoplasm. liiheril.-uiee tliroimh 

 the chromosomes" mean- that th<' rhrouiati<' -iih-taii.M' 

 of the nucleus is the locus ot' deterniiiiei-s. ;ind ^iiier t"h(^ 

 nuclear content of egg and -pei-ni is e(inl\nh'!it thi> iiiu>t 

 also mean an e(|iial determinative sliai'c liy egg and sj)erm 

 in heredity. 



