1909-10.] Nervous Mechanism of Alimentary Canal of the Bird. 335 
to hinder penetration, and had to be abandoned. The percentage of failures, 
however, still continued high, and small variations introduced experiment- 
ally into the technique resulted in no improvement. Up to this time 
perfectly fresh tissue had been used, on the assumption that the fresher the 
tissue the greater were the chances of success. An experiment was, 
however, tried, in which a chick which had undergone a certain degree of 
post-mortem change was subjected to the stain. The result was so good 
that a series of experiments were made both on adult and embryonic tissues, 
and it was found that much more satisfactory results were got if post- 
mortem changes were unchecked for a certain number of hours. The 
results of these experiments may be tabulated as follows : — 
A. Embryonic Tissue. 
1. With chicks of two to three days’ incubation the best results 
were got with perfectly fresh tissue. 
2. With chicks after three and a half to four days’ incubation the 
best results were got where post-mortem changes of not more 
than twelve hours had taken place. 
3. With chicks after four and a half to five days’ incubation 
excellent results were grot where the tissue underwent from 
twelve to twenty-four hours’ post-mortem change. 
4. With chicks after six and seven days’ incubation post-mortem 
changes of twenty-four hours may be allowed to elapse. In 
the case of chicks of just six days’ incubation, however, the 
full twenty-four hours’ change was rarely tried ; eighteen to 
twenty hours’ change was generally found most successful. 
5. With embryonic dogfish, where the gut was sufficiently 
developed to allow of its being removed, changes of twenty _ 
four hours’ duration were found to be associated with a very 
high degree of success. 
B. Adult Tissue. 
1. Brain and spinal cord stained excellently if twenty -four to 
thirty-six hours were allowed to elapse between the death of 
the animal and the treatment of the tissue. 
2. The plexiform nerve mechanism in the intestinal wall of an 
adult animal rarely showed a satisfactory reaction to the 
stain unless twelve to twenty-four hours elapsed between the 
death of the animal and the staining of the tissue. 
3. An investigation which was made on the nerve supply of 
the ovary led to the observation being made that the best 
