70 REGI/E SCIENTIARUM 



Ann. adeo radios luminis pcr eam ad choroidcm dcduci polFe ; nam oculi bovi» 

 1669. recemis lclerotica fublata lumen non pcnctrat rctinam. Ergo hasc lunica 

 vidcmr potius villonis organum , non cnoroidcs. 



Id conllqucns c(Tc negabat D. Mariottc cum magnum fit difcrimen intcr 

 anim.ilis mortui rctinam aifri cxpofiiam ^' eam quac in vivo animantc intcr 

 vitrcum humorcm & choroVdcm accuratc concluditur. Rctum qu.ilintes 

 paulo momcnto immutari aitb.it , corncam tunicam qua: pellucct , in aere 

 calido brevi tempore opacam fieti. Quin ctiam in oculo bovis adhuc ca- 

 lentc & in duas partes fcfto , adeo ut rctina vitrcum humorcm adhiic in. 

 voluat , tum varii colorcs chotoidis , balls itidtm nervi opttci , vafa ex 

 eo in rctinam fparfa , fic m confpedum veniunt , ut rctiformis tunica vix 

 difcerni qucat. 



Nec propterea tamcn omncm albcdincm rctinar dctraifl.im voLbat , prx- 

 fcrtim in ca parte qua tangit choroidcm ; idque a natura piovifum aicbatr 

 ut nimium vegetioris luminis fplendotem tcmperct , quemadmodum cutis 

 epidermide obducitur , nc la-datur a corporibus qua: tangit. 



III. Quin Sc ratio a D. Pecquct propofita perp.irvi elfc momenti cidcm 

 vidtbatur , tum fubiiliores pattcs in rctina moitui aninnlis difflatx, opa- 

 citatcm quandam inducant , fcrc ut charu madens ptlkicct , cxficcnta fit 

 opacior. Sic in multis animantibus in mcdio cryftaliini humoris nii- 

 cleus quidam cft pcllucidus qui intra paucos dics albus fit & opacus , 

 ctiara intia oculum conclufus , cum tamcn cxtctior cryftallinus adhuc 

 pclluccat. 



IV. Ar enim retina aqui iinmcifa albcdincm fuam & opacitatem na- 

 tivam prodit : Ita cft , ftd vitrti humoris partc in vafc immcrfa tunica 

 hyaloides qui omnino cft dinphana inftar tela: arancx , alba quoquc vide- 

 bitur. Quin & cryftallinus in aqua opacitatcm quandam conrrahit , Sc 

 congclatus inftar nivis candicnr. Non mirum igitut fi rctina ante aiiti cxpo- 

 fita & aqux immcrfa nonniliil albcdinis pra; lc fcrat. 



V. Quamobrcm ut liquere pofllt an radii luminis pcnc intcgri ad 

 choroidem pervcniant , aii potius m rctim ipfa fiftaniur , utraquc mm 

 choroitks , tuni rctina iii ftatu fuo naiuiali Ipcft.inda tft. Expcricntia ipfa 

 retinam traiuccre compcricmus , h candcla acccnia de no(5le propc ocuIcJs 

 coUocetur , idque faciamiis ut canis oilo aut dtccm paftibus rcmotus nos 

 afpiciat , tum cnim lumen in illius oculis fplendidum intutbimur c radiis 

 rcflcxis a choroidc canis multum candida & fplcndida. Nam fi a crNftal- 

 lino , nut rctina prodiret vcgctum illud liimen , iilcm evcniret iii hominc 

 & avibus , quibus choroidcs atra tft : lcd non tft ita. IJ vcro ita cvcnic 

 in canc quod ladii luminis pcr cryftallinum tra)cct;i in choroidc velut in 

 foco colligantur , iiquc (k rcflliant iit focus reciprocus fic in acccnfi can- 

 dcla. Unde oculus huic vicinior cryftallinum cinis humotcm adm.)dum il- 

 Iiiminatum intucri debct, uti in opiica dcmonftratur. Idque cxpcriri faciic 

 tft fi phiala vitrea & lotunda aqua pura iniplcatur , caquc odo aut dcccm 

 paflibus ab acctnfa facc rtmovcatur , riim rctro phialam ad ftniidiamctri 

 lux dirtantiain chartam candidam a.imoveas , in qna lux qux phialam pc- 

 nctravit , lanquam in foco coUigitur ; lum cmm oculus prope faci.m 



