Among the charactn-s of neuroseci*etoi.?-cells in tlic hypothalamus of humans arid other mammal-( (Xaupp and Schtzrrcr, '35) one seems suspect : there are ~1 1 s staining dalker arid other stairiiiig lighter t h r l the avtii*agc of tlie cells of tllc iiucleus supraopticus. Ti1 view of tlrr fact tliat Yissl ( '10) demonstrated the artificial shrinkage aiitl inflation of iierve cells arid tlie further fact that the dark cclls in the spinal ganglia whiel1 Kiss belicved to he sympathetic cells turiied out to he artefacts (Fisher arid Ranson, '34) it wcmed advisa1)le to of tlie uiiequal staining ol' those cells mow 111 doing this the literatiwe on a closely relatetl problem, i.c., the question of tlie d a r k aiid light livcir cells was eiicoiiii Those cells off'cred a way to check the results obtaiiicd iii iiivestigatiiig the s u l q m d l p artificial cliaracter of the d a ~k a r i d light iierve cells in the sapi.aoptic nucleus.
On the basis of former ohsen-atioris (Scliaiwr, 'X3, '34' '37) it was thought that iii the liver as well a s in the hi.airi, dark a i d light cells might bc brought about ar+ficially 1))pix aiid tpariiig the fresh tissue wlicii tlic hraiii is rcmo\*ecl from tlie slinll 01-pieces tire cut out f r o m tlic liver. It with cspectcd tliat perfusion of the hrnin and the liver with the lisiiig Aaid would giw different iwults, as the fixcd cell could 110 longer asciihing to them a furictiorial rncaiiing.
' Itockrfrller Fellox. Tliis research xm& aided h j a grant to 'l'he I-iiivrrsit> of f'liicago 1 3 7 tlie Boekefelict Founda tiori.