[38] 



EXPLANATION OF PLATES L & II. 



Plate I. 

 Fig. 1. — A. — Unfertilised ova, Sept., 1880, nucleus extracted. 

 B. — Ditto, nucleus in nitu. 

 C. — Nucleus extracted from A. 

 €, dark external envelope ; g., granular mass ; n., nucleus. 



,, 2.— A.— Fertilised ovum, Feb. 27, 1887, light pole. 

 B. — Ditto, ditto, dark pole. 

 C. — Nucleated cell, x 125. 

 D. — Non-nucleated cell, x 125. 



„ 3. — Fertilised ovum, March 3, 1887, x 50 ; showing ep. , epiblast ; 

 hy. , hypoblast, forming under it. 



,, 4. — Section from another egg, same date, x 25, showing c. , trans- 

 parent envelope formed of three layers ; hy., hypoblast ; 

 ep., epiblast; md.g., medullary groove. 



,, 5 and 6. — Two sections taken from one egg, March 4, in which 

 the medullary plate and cornua are seen forming more com- 

 pletely ep. , epiblast ; liy. , hypoblast ; c. , cornua. 



Plate II. 

 Figs. 1 — 13. — Thirteen sections cut from one egg, March 5, and follow 

 in rotation according to the numbers, ms. , mesenteron ; 

 nc, notochord ; ep., epiblast ; hy., hypoblast ; j/i., niesoblast; 

 y, yelk mass ; c. , body cavity. 



The Use of Pearl-Shells. — The pearl-shells shipped from 

 Australia to the United States and Europe, are used principally 

 for the manufacture of knife-handles, shirt-buttons, etc. Con- 

 siderable quantities arc also used for papier-mache and other 

 ornamental work. The pearl buttons, shirt-studs, etc., now made 

 in the United States are said to be the best and cheapest in the 

 world, a fact due in great measure to the care in selecting the 

 material, and to the improved methods of cutting. — Bull., U.S., 

 Fish. Comm. 



The Manchester Microscopical Society. — In the report 

 of this Society, in our October issue, we should have stated that 

 Mr, J. L. W. Miles was President in i886, and that the President 

 for 1887 is Professor A. Milnes Marshall, M.D., M.A., D.Sc, 

 F.R.S., F.R.M.S., etc. 



