STOMATA OF THE CAPILLARY LYMPHATICS. 309 



a means of staining the tissues; but have met with them 

 under so many different conditions, that I am not at present 

 satisfied of their nature. In perfectly fresh silvered prepara- 

 tions, preserved as carefully as possible in their natural condi- 

 tion, we frequently meet with areas of considerable extent in 

 which scarcely any openings are present, whilst in others, 

 again, they are very numerous ; the difference being in no 

 way attributable to the mode of preparation. At the same 

 time, it cannot be denied that within a few hours after death, 

 or as a consequence of mechanical violence, or careless prepara- 

 tion, they always appear more numerous, clearly on account 

 of the epithelial cells becoming detached from each other. The 

 variability in the appearances presented by perfectly fresh 

 specimens may be explained on the supposition that at certain 

 times, or under certain conditions, connected with the imbibi- 

 tion of fluids, the substratum of the epithelium opens, whilst 

 under other conditions it closes up. At present no absolute 

 proof has been adduced to show that they are really openings, 

 nor has any one shown that solid particles can traverse them. 



I must express myself in exactly the same terms in regard 

 to the very regular and interesting appearances of a similar 

 nature, situated for the most part at the points of junction of 

 several epithelial cells, which are frequently exhibited in the 

 lymph vessels of silvered preparations, but which are some- 

 times undiscoverable even when the greatest care has been 

 taken in the preparation of the specimen. I endeavoured to 

 obtain them constantly, and hoped, in accordance with what 

 has been above stated, to accomplish this by permitting the 

 central tendon to lie for several hours in diluted pericardial 

 fluid, thus rendering its tissues as moist as possible with an 

 indifferent fluid, yet without being able to observe the spaces 

 occur with such constancy and regularity as, after the foregoing 

 exposition and the observations I have still to make, was to be 

 desired. The present condition of our knowledge may there- 

 fore be expressed in these terms, that stomata can be certainly 

 proved to exist in certain lymphatic capillaries ; that openings, 

 at least of an occasional character, must also exist in other 

 lymphatics, especially in absorbing membranes, though this still 

 remains to be satisfactorily demonstrated, notwithstanding that 



