log 



This method, which is longer than Method i, 

 requires more dissecting and teasing out in order to 

 isolate the glands cleanly, and, as we have said, may 

 still be followed, even if No. I has failed ; but our 

 experience has been that Method I is learned at once 

 without any difficulty. 



Fig. 44. Microscopic Structure of Salivary Acinus and that of a Newly- 

 Hatched Mosquito (right) 



Ascertain that the glands of either side consist 

 of three acini, the ducts of which join almost imme- 

 diately after leaving the acinus to form a single long 

 duct. 



1. Observe that of the three glands of each side 

 (Figs. 43 and 46) :- 



(i) Two are highly refractive, and the cells in 

 these are very distinct and clearly defined (lateral 

 glands). 



(ii) One is much less refractive, and the com- 

 ponent cells are much less easily defined (central gland). 



2. Observe that each acinus has a duct running 

 through its whole length, and that the secretory cells 

 form a single row around this. 



3. Observe that each secretory cell has a large 

 mass of clear secretion within it, forming the chief 

 bulk of the cell, and that the nucleus is flattened and 

 pushed to the periphery (Fig. 44). Pressure tends to 



