The röle of the chondriosomes in the cells of the guinea-pig’s pancreas. 257 
If the right stage has been attained, the sections should present quite 
a dark grey colour to the naked eye. The sections, after rinsing in tap 
water, should then be transferred to a saturated aqueous solution of 
Thionin for from twenty to thirty minutes. The excess of stain is then 
washed away in water, and the sections passed rapidly through 30%, 
50% and 70% alcohols to absolute alcohol. At this stage, the cytoplasm 
still retains some of the Thionin, which is finally removed from everything 
except the nuclei by counterstaining with Orange G. dissolved in Clove 
oil, for not more than two minutes, followed by xylol and canada 
balsam. 
The chromatin and the nucleoplasm are blue or grey-blue, the chon- 
driosomes on the other hand do not retain the Thionin and therefore 
present a deep black appearance, in striking contrast to the nucleus. 
By comparison ot the tissue fixed in Zenker or strong Flemming, 
with that fixed in Benda’s solution or Altmann’s bichromate-osmic, 
it is easy to ascertain which are chondriosomal bodies and which are 
nuclear, since the first two fixatives do not preserve the chondriosomes 1 ). 
Also, by using different stains, a further measure of precaution may be 
obtained, since the chondriosome has no affinity for saffranin after fixa- 
tion with any of the fixatives before mentioned. 
The pancreas used in these observations was obtained from four 
guinea-pigs. 
Guinea-pig I. This after being starved for 24 hours, was killed 
and portions of the pancreas removed and fixed. 
Guinea-pig II. was killed two hours after feeding. 
Guinea-pig III. weight 0.6 kg. This was sufficiently fed, after 
a period of starvation of 15 hours. 
a. Six hours after the meal, a portion of the pancreas was removed 
under an anaesthetic, and fixed. 
b. Half an hour after the Operation, 1 / 80 grain of pilocarpine nitrate 
was injected into the groin, and one and a half hours after the 
injection, when salivation was noticeable, the animal was killed 
and portions of the pancreas removed and fixed. 
Guinea-pig IV. weight about 0.5 kg. This animal was starved 
for 24 hours, and 
c. a piece of the pancreas was removed under an anaesthetic and fixed. 
*) As remarked above, Flemming’s strong solution does occasionally preserve 
the chondriosomes, in a very poor manner, but if the pieces of tissue be kept in it 
for 24 hours or more, I find that those bodies cannot be demonstrated at all. 
