No. 641] IXHERITAXCE OF CAXCEE IX MICE 525 



the ovary is Ihc main t'at-toi- and suspension of breeding 

 plays only a sulxii-diiiatc role, in the ease of resistance 

 to other death prodiieiiii;- conditions, the suspension of 

 breeding seems to be the main factor and the flimination 

 of the ovarian function only a subsidiat> ract(M' which 

 merely acts through the suspension of luccdinu' which it 

 calls fortli or in wldch at Usast the susi.msion ..f hiviMUng 

 is by far the moiv si-id li<-aid factor. W'r found :hat the 

 dinVrcnccs in the teinhaicy i.. die fn.ni other causes than 

 caiu-er which we oh>rfve n<M-nially hi^tween different 



eliminated in mic which are prevented Tr-nn brc-ding. 

 All those strains in which breedin- is prev.nited brcome 

 Ion- live(h If a dilference in the .hiration of lifr should 

 still exist l)etween diff.Mvnt nond.reedin- st rain^. it must 

 be veiw much smadei' than that between breedin- strains. 

 Furtht>rmore. tiie ditforence in the ionu'evity between non- 

 brerdln- mire an.l ca>tratrd mi.-e is likewise v.mw >mall 

 and this is the reas.in why -ve comdude that castration 

 ])rolmms the life of Miicr mainly thn.uali its rtfeel on 

 l)reeding. As far as th.' cancel- rate is eom-ei-ned. on the 

 other hand, we have shown that castrathni at an early a,ue 

 is much more .dTective than i)revention of bive.linu'. 



II. In man it has been observed by >..veral authors 

 that in older individuals ^nffrrin- fi-om cancer a mul- 

 tiplicitv of slidit malh.rmalio,,.. ,.ftrn .lu.' apparMitlv to 

 a misplacenu'ut <.f end.rvonal lissur. ..r a multlplh-itv of 



< nd.ryonaldevrlopniont play a .-rrtain part! and in whieh. 

 as a r.-nlt .d' thi- uvn; i-nl tendency, varion^ kind^ of 



