168 WILLIAM WALLACE. 



Tnent and degrees of ripeness. Observations were also made, 

 mainly at Plymouth, on ovaries of the following species : — 

 Pleuronectes platessa, P. limanda, Sy gnathns acus, 

 Zeus faber, Salmo tratta, Spinax niger, and Chimasra 

 monstrosa.^ 



Methods. — Only preserved material was employed in this 

 research. The ovaries of Zoarces were, for the most part, 

 fixed in Bles's fluid — a mixture of alcohol, formol, and acetic 

 acid. The stains then used were borax carmine — either 

 alone or in conjunction with picro-nigrosin — and htemalum 

 and eosin. Other material of Zoarces, after fixation in 

 Hermann's platino-aceto-osmic mixture, was stained with 

 thionin. Cytoplasmic and nuclear structures are brought out 

 very sharply by stains after fixation in Bles's fluid. 



The ovaries of Spinax and Chima?ra were fixed in Bles's 

 fluid, and stained either with borax-carmine and picro-nigrosin 

 or with Heidenhain's iron-hsematoxylin (long process) and 

 orange G. The latter combination gave by far the most 

 satisfactory results of any 1 have tried, Mann's methyl blue- 

 eosin (1893) was also tried. By this method the red blood- 

 corpuscles and the nucleoli of the germinal vesicle are the 

 only structures to retain the eosin ; the rest, nuclear reticu- 

 lum, lanthanin, cytoplasm, etc., are all in various shades of 

 blue and green. This result is rather surprising in view of 

 Carnoy and Lebrun's conclusions ('La Celkile,' xii, xiv, xvi) 

 in regard to the chemical nature of these nucleoli. These 

 investigators hold it as proved that the nucleoli of the 

 germinal vesicle in amphibians and fishes are parts of the 

 chromatin or nuclein element. Since they contain a high 



of St. Andrews. I have to thank Prof. Mcintosh for suggesting the subject 

 and for the khidly interest he took in the work. 



While at Plymouth I held an 1851 Exhibition Research Scliolarsiiip. My 

 thanks are due to the authorities of the Biological Station for granting me 

 accommodation and ample supplies of material and reagents. 1 am under 

 especial obligations to the Director, Dr. Allen. 



' Por the ovaries of Spinax and Cliimttra I am much indebted to Mr. 

 R. C. Punnett. 



