246 NATURAL SCIENCE. Oct., 



" Lastly, in this connection I would state the results of my 

 experiments. I worked with a number of fish, and always with the 

 same success ; but I shall here only refer to one case — that of the 

 dabs (Pleitronectes limanda). That they were sight-feeders was 

 evidenced by their behaviour when I lowered a closed tube 

 full of water, and with a worm in the middle of it, into their 

 tank ; time after time they bumped their noses against the glass 

 at the very spot where the worm was situated. That they could 

 also recognise the smell of food, apart from seeing it, was demon- 

 strated in various ways. First, if instead of a closed tube, as in the 

 last-mentioned experiment, one open at the bottom was used, after 

 a short interval the nosing at the part where the worm was seen 

 ceased, and the lower end of the tube, from which, doubtless, worm-juice 

 was diffusing, was vigorously nosed. If, again, instead of putting 

 worms into a tube I placed a number of them in a closed wooden box 

 with minute apertures to let water pass in and out, there was a 

 similar excitement produced, and the dabs hunted eagerly in every 

 direction. When water in which many worms had lain for some 

 time was simply poured into the tank through a tube that had been 

 in position for several days, and by a person who was out of sight of 

 the dabs, the results were most marked. In a few seconds hunting 

 began, and in their excitement the dabs frequently leapt out of the 

 water, apparently at air-bubbles, and on one occasion one even cleared 

 the side of the tank, which was about two inches above the water, 

 and fell on to the floor of the aquarium. Yet there was nothing 

 visible to stimulate this quest." 



The Thyroid Gland. 



In the August number of our excellent contemporary, the Medical 

 Magazine, Mr. Lorrain Smith has an interesting paper on the thyroid 

 gland, which, as everyone knows, is the fashionable subject in current 

 Pathology. It has been shown recently that many glands in the 

 mammalian body have, at least, a double function : they form their 

 special secretion as the liver, for instance, forms bile, or the kidneys 

 remove nitrogenous material from the blood ; but in addition they 

 have some part to play in the general economy of the organism. 

 Their loss by disease or excision not only prevents the formation of 

 the special secretion, but disturbs the general economy of the body. 

 The thyroid is a gland limited apparently to the second form of 

 activity. This activity is at present being sought for : some results 

 go to connect it with the regulation of heat ; others with the general 

 metabolism of the body. So far physiologists have not paid much 

 attention to the comparative anatomy and development of the thyroid, 

 hut, without question, this side of the subject will raise problems of 

 very general interest. It is, for instance, most probable that the 

 thyroid was originally a slime-secreting organ correlated with the 



