CuAP. XVII.] SUMMARY ON ABSORPTION". 341 



tion which had been kept during several days in a warm room, 

 and their glands were not at all affected wlien examined after 

 21 hours. 



A weaker solution of one part of urea to 437 of water was 

 next tried on six summits, all carefully examined before being 

 irrigated. The first was re-examined after 8 hrs. 30 m., and the 

 glands, including the spherical ones, were brown; many of the 

 oblong glands having their primordial utricles much shrunk and 

 including granules. The second summit, before being irrigated, had 

 been somewhat affected by the surrounding water, for the spherical 

 glands were not quite uniform in appearance; and a few of the 

 oblong ones were brown, with their utricles shrunk. Of the ob- 

 long glands, those which were before colourless, became brown in 

 3 hrs. 12 m. after irrigation, with their utricles slightly shrunk. 

 The spherical glands did not become brown, but their contents 

 seemed changed in appearance, and after 23 hrs. still more changed 

 and granular. Most of the oblong glands were now dark brown, 

 but their utricles were not greatly shrunk. The four other speci- 

 mens were examined after 3 hrs. 30 m., after 4 hrs. and 9 hrs.; 

 a brief account of their condition will be sufficient. The spherical 

 glands were not brown, but some of them were finely granular. 

 Many of the oblong glands were brown; and these, as well as 

 others which still remained colourless, had their utricles more or less 

 shrunk, some of them including small aggregated masses of matter. 



Summary of the Observations on Absorption. From the 

 facts now given there can be no doubt that the variously 

 shaped glands on the valve and round the collar have the 

 power of absorbing matter from weak solutions of certain 

 salts of ammonia and urea, and from a putrid infusion of 

 raw meat. Prof. Cohn believes that they secrete slimy mat- 

 ter; but I was not able to perceive any trace of such aclion, 

 excepting that, after immersion in alcohol, extremely fine 

 lines could sometimes be seen radiating from their surfaces. 

 The glands are variously alBFected by absorption: they often 

 become of a brown colour; sometimes they contain very fine 

 granules, or moderately sized grains, or irregularly aggre- 

 gated little masses; sometimes the nuclei appear to have in- 

 creased in size; the primordial utricles are generally more or 

 less shrunk and sometimes ruptured. Exactly the same 

 changes may be observed in the glands of plants growing and 

 flourishing in foul water. The spherical glands are gener- 

 ally affected rather differently from the oblong and two- 

 armed ones. The former do not so commonly become brown, 

 and are acted on more slowly. We may therefore infer that 

 they differ somewhat in their natural functions. 



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