EXPLANATION OF THE PLATES. 



It is to be understood, that all the figures given in the following plates 

 are magnified 670 times, unless when the contrary is stated. 



PLATE XL 



MUCUS. 



Fio-. 1. Mucus corpuscles of their ordinary size, form, and 

 appearance. 



Fig. 2. The same collapsed, owing to the density of the fluid 

 in which they are contained ; these corpuscles are 

 capable of resuming the circular form by the addi- 

 tion of water. 



Fig. 3. Represents the action of water on the mucus cor- 

 puscles, in which they increase very considerably in 

 dimension, the nucleus which is usually single 

 becoming at the same time more distinct. 



Fig. 4. The same acted on by very dilute acetic acid, under 

 the influence of which the originally single nucleus 

 becomes divided into two parts, the portion of the 

 corpuscle external to these remaining granular. 



Fig. 5. Exhibits the action of undilute acetic acid, under 

 which the nucleus becomes divided into from two 

 to five or even more parts, the enveloping portion 

 of the corpuscle losing its granular texture, and 

 appearing perfectly smooth and transparent. 



Fig. 6. Mucus corpuscles in process of development, ex- 

 pressed from the cavity of a gland situated in the 

 mucous membrane lining the upper portion of the 

 rectum of a child who died of English cholera. 

 9 



