130 s. HATTA. 



of Gull, and my special thanks are due to him for placing them at my 

 disposal. The other part of the materials was obtained by myself at the 

 same place during the spring of the present year (1891). We wish to 

 express our deep obligations to Mr. Nawa, the enthusiastic naturalist 

 of Gifu, without whose aid we could not have succeeded in obtaining 

 the objects of our search, and to the authorities of the Middle, and of 

 the jS^orma], Schools of that town for affording us laboratory accom- 

 modation. 



The eggs and larvœ were hardened partly in Kleinenberg's picro- 

 sulphuric acid, and partly in corrossive sublimate. A few larvœ were 

 also killed in Flemming's solution. The sublimate specimens gave 

 the best results, although good sections were obtained in all cases. 

 Acids, on the whole, had the effect of making yolk-granules highly 

 refractive, and thus greatly increased the difficulties of observation. 



As to the staining fluids, picro-carmine gave by f;xr the most 

 satisfsictory results. This, being the nuclear stain and not affecting 

 yolk granules, made observation comparatively easy. Other colouring 

 fluids like borax-carmine or haematoxylin (of Kleinenberg as well as 

 of l>(jhmer) stained diffusely both the protoplasm and the nuclei, and 

 above all, were most unsuited for my purpose from the fact that they 

 stained yolk granules the deepest. 



Tlie age of the eggs and of the lar^-œ was not determined by the 

 actual time elapsed, but by their appearances as opaque objects and by 

 their structure as shown by sections. 



Care was taken to have sections of each stage made in several 

 planes so as to enable us to obtain as accurate an idea as possible of it. 



1 shall give the results of my investigation under the following- 

 heads : — 



1. The (lastrulation. 



2. The Formation of the Mesoblast. 



