240 On the Thyroid Gland of the Dog. [Jan. 27, 



The mean annual secular change observed, 8' 5"*72 declination dimi- 

 nishing, is larger than that determined by Sir E. Sabine, which was 

 7' 39" ; but this is only in accordance with the opinion expressed in the 

 former paper, where it is shown that the secular change is a variable one, 

 and is probably now becoming progressively more rapid. 



The semiannual inequality is also largely increased, being now 

 81 /# 80, whereas between 1857 and 1862 it was only 58"-85 ; possibly 

 part of this difference may, however, be due to the fact of the observa- 

 tions now under notice having only been made at isolated periods, whilst 

 the latter result was obtained from the hourly readings of the magneto- 

 graph recording the declination continuously. 



The observations discussed in this paper have been made and reduced 

 by Mr. Gr. M. Whipple, B.Sc, Magnetic Assistant, and Messrs. Callum, 

 Power, and Eigg, observers, under his supervision. 



III. " Contributions to the Minute Anatomy of the Thyroid Gland 

 of the Dog." By E. Cresswell Baber, M.D. Lond. Com- 

 municated by Dr. Klein, F.R.S. Received December 9, 

 1875. 



(Abstract.) 



The minute structure of the thyroid gland generally, and of its 

 lymphatics in particular, are subjects still but imperfectly understood. 

 "With the view of elucidating the latter, the following research was made 

 on the thyroid gland of the dog. The research was carried out under the 

 direction of Dr. Klein. On injecting the lymphatics of this organ with 

 Berlin blue, by the method of puncture, they present the following 

 characters : — 



Traversing the gland, chiefly in a longitudinal direction, are large 

 lymphatic vessels provided with valves. In direct connexion with these, 

 and permeating the gland in all directions, is a dense meshwork of 

 lymphatic tubes and spaces. The smaller lymphatic tubes run between 

 individual gland-vesicles, the larger between groups of the same. They 

 accommodate themselves accurately to the intervals left between the 

 vesicles, and where the intervals are larger they expand into irregularly 

 shaped lymphatic spaces. They present no appearance of terminating in 

 blind extremities as stated by some authors. Injections with nitrate of 

 silver show the lymphatic vessels, tubes, and spaces to be all lined with 

 a continuous layer of endothelial plates. 



During this investigation it became necessary to study more care- 

 fully the interalveolar tissues. This led to the discovery in them 

 of a tissue which does not appear to have yet been described. This 

 tissue, which is designated by the author by the name of "parenchyma " 

 consists of large rounded cells, each provided with an oval nucleus, 

 found either singly or in groups amongst the epithelial cells. Erom 



