282 CHI PING 
For comparison and control a second limited series of inbred 
albino rats was also used. The data for this series are given on 
page 303. Up to the introduction of this series the paper deals 
only with albino rats of the ‘standard’ strain. 
TECHNIQUE 
The rat was etherized and, after the necessary measurements 
had been noted, was completely eviscerated. The superior 
cervical sympathetic ganglion was removed from each side. In 
the removal care was exercised to avoid distortion of the tissue, 
for mechanical injury to the ganglion is likely to affect the size 
and shape of its cells. As the ganglion is small, it was deemed 
necessary to remove it in the mass of other tissues which closely 
invest it. 
Both ganglia from each rat were prepared, but only one was 
used for measurements. No distinction between right and left 
was made in the record. 
Aiming at a satisfactory preservation of the natural size of the 
cells, I followed King’s (?10) recommendation of Bouin’s solution 
for fixation. The ganglia from older rats were fixed in the solu- 
tion for twenty-four hours, while for those from the younger 
ones—from birth to twenty-five days old—the period was reduced 
to twelve hours. Such a reduction of the fixation period has 
given satisfactory results. 
The specimen was washed in different grades of alcohol, from 
70 to 98 per cent, containing a small amount of carbonate of 
lithium. By so doing the yellow tinge given to the tissue by the 
fixation was completely removed. ‘The specimen stayed in the 
alcohols of lower grades for twelve or more hours, and in the 90 
and 98 per cent alcohol for about one hour. It was finally trans- 
ferred to cedar oil for twenty-four hours for complete dehydra- 
tion. Paraffin of 52° was used for imbedding. By employing 
an electric bulb above the container the paraffin was kept melted 
only in its upper layer in the jar, the specimen sinking to the 
contact line between the melted and unmelted paraffin. 
Under these conditions the specimen could be left in the 
paraffin for thorough penetration as long as seemed necessary 
without danger of overheating. 
