grains，thisisequivalentto62cubicinchesofwater；sothatasbrainisheavierthanwater，weareperfectlysafeagainsterringonthesideofdiminutionintakingthisasthesmallestcapacityofanyadultmalehumanbrain。Theonlyadultmalebrain，weighingaslittleas970grammes，isthatofanidiot；butthebrainofanadultwoman，againstthesoundnessofwhosefacultiesnothingappears，weighedaslittleas907grammes（55。3cubicinchesofwater）；andReidgivesanadultfemalebrainofstillsmallercapacity。Theheaviestbrain（1872grammes，orabout115cubicinches）was，however，thatofawoman；nexttoitcomesthebrainofCuvier（1861grammes），thenByron（1807grammes），andthenaninsaneperson（1783grammes）。
Thelightestadultbrainrecorded（720grammes）wasthatofanidioticfemale。Thebrainsoffivechildren，fouryearsold，weighedbetween1275and992grammes。Sothatitmaybesafelysaid，thatanaverageEuropeanchildoffouryearsoldhasabraintwiceaslargeasthatofanadultGorilla。
Nodoubt，thisisaverystrikingdifference，butitlosesmuchofitsapparentsystematicvalue，whenviewedbythelightofcertainotherequallyindubitablefactsrespectingcranialcapacities。
Thefirstoftheseis，thatthedifferenceinthevolumeofthecranialcavityofdifferentracesofmankindisfargreater，absolutely，thanthatbetweenthelowestManandthehighestApe，while，relatively，itisaboutthesame。ForthelargesthumanskullmeasuredbyMortoncontained114cubicinches，thatistosay，hadverynearlydoublethecapacityofthesmallest；whileitsabsolutepreponderance，of52cubicinches——isfargreaterthanthatbywhichthelowestadultmalehumancraniumsurpassesthelargestoftheGorillas（62-34-1/2=27-1/2）。
Secondly，theadultcraniaofGorillaswhichhaveasyetbeenmeasureddifferamongthemselvesbynearlyone-third，themaximumcapacitybeing34。5cubicinches，theminimum24cubicinches；and，thirdly，aftermakingalldueallowancefordifferenceofsize，thecranialcapacitiesofsomeofthelowerApesfallnearlyasmuch，relatively，belowthoseofthehigherApesasthelatterfallbelowMan。