CHEMOPOTENTIALS IN GIANT NERVE CELLS 183 



The differential sensitivity of the nerve cells under anoxia was also found by 

 Kolmodin and Skoglund in mammalian neurons, the interneurons of the cord 

 being more resistant than the motoneurons. The same authors also found a 

 depolarization of about 5 to 10 mV during 30-sec asphyxia. So, if we assume 

 that about 10 mV/min is an anoxic mean depolarization rate for the mam- 

 malian neuron (ten times more than for Aplysias somata), a parallelism may 

 exist between respiratory rate and depolarization rate: The ^o., for Aplysid's 

 somata is 170 /xl/g per hr, whereas for mammalian nerve cells it is ten times 

 greater (Chalazonitis, 1959; Chalazonitis and Otsuka, 1956). 



It would also follow that in systems such as the peripheral nerve system, 

 which has an extremely low respiratory rate, the effects of anoxia upon the 

 resting potential will be comparably slower. This is well known to be the case. 



3. BIOCHEMICAL EVENTS DURING ANOXIA 



Before discussing this question we shall give some data on the general 

 cyto-chemical organization of these cells. 



(a) Data on the Cytocheiiiical Organization of the Cell 



First, each one of the giant somata has its own capillary net, directly ex- 

 panded on its surface (Plate I, Figs. 3 and 7; Plate II, Fig. 11). It was found 

 in a series of experiments in which ganglia were injected with Janus green B, 

 that Br and A are among the cells with the densest vascular nets. 



Generally the cytoplasm surrounding the nucleus is more basophilic (Plate 

 I, Figs. 5, 9, 10; Plate II, Fig. 12). Evidence has been presented elsewhere for 

 ascertaining that it is in this region that the maximal dehydrogenase and de- 

 carboxylase activities of the cell are to be found (Chalazonitis, 1959). 



At the periphery of the highly basophilic cytoplasm one observes a thick, 

 regularly pigmented layer (Plate I, Figs. 5, 9, 10; Plate II, Figs. 13, 14). In 

 the majority of the cells the higher density of this layer is in the axon hillock 

 area of the cell (Plate I, Fig. 9; Plate II, Fig. 13). However, the axon itself is 

 weakly pigmented (Plate II, Fig. 13). 



In many cases there is irregular distribution of pigment, some areas having 

 more pigment than others (Plate II, Fig. 14). The pigment is located in small 

 granules, "grains" or hpochondria (Chalazonitis and Arvanitaki, 1956; 

 Young, 1956) (Plate II, Figs. 15, 16). 



Lipochondria whose diameter is between 0- 8-0-1 /<. are highly osmio- 

 phjlic (Fig. 19) and their cortex is darker than their interior (see Chalazonitis 

 and Lenoir, 1959). 



The chemical identification of lipochondria pigments is given elsewhere 

 (Chalazonitis and Arvanitaki. 1956). Here the existence of two pigments, 

 haemoprotein (haemoglobin-like) and carotenoid, is concluded from the 

 data of Table 2. 



