46 Prof. M^ntosh's Notes from the 



which bore the journey and the heat more satisfactorily, pre- 

 sented at the twenty-fourtli hour, viz. about 5 P.M. on the 22nd, 

 the germinal cavity and shield. As the embryo became out- 

 lined next day (2;}rd) a tendency to the formation of nume- 

 rous large vesicles, at the ordinary site of Kupffer's, as well 

 as extending forward along the body in groups, was a con- 

 spicuous feature. How far this condition was due to the 

 vicissitudes the ova had encountered is an open question, but 

 it was pronounced. On the 24th June the embryo was 

 distinctly outlined with optic vesicles, lenses, cardiac thick- 

 ening, and other features, while the large vesicles above 

 mentioned were fewer. Moreover in some a series of chroma- 

 tophorcs were thickly dotted along the trunk and a few over 

 the brain, but no colour was yet visible under a lens, though 

 the embryo was indicated by a distinct opacity. 



On the 25th June the ova presented a slightly reddish hue 

 under a lens. It was also interesting to note that the diameter 

 of some of them had increased in the direction of the long 

 axis of the embryo, so that they were ovoid. The head and 

 body were studded with I'ounded reddish (ruby-red by trans- 

 mitted light) chromatophores, some, however, being only 

 slightly tinted ; they likewise extended over part of the 

 yolk. The protoplasmic investment of the oil-globule had a 

 few black specks. The otoeysts were well formed, the lenses 

 distinct, and the heart pulsated feebly at intervals. The tail 

 had extended considerably beyond the yolk, yet one or two 

 vesicles occurred on the site of Kupffer's. The yolk had a 

 streaked granular aspect, probably from the development of 

 minute vesicles on the blastodermic surface. The notochord 

 was multicolumnar. 



Next day the pigment-corpuscles had a darker ruby-red, 

 and black chromatophores had also appeared. The pectoral 

 expansions were distinct, the vesicles had vanished from the 

 ventral aspect of the trunk, while the tail was longer and had 

 a few black chromatophores near the tip. The black pigment 

 at the oil-globule had increased. The pulsations of the heart 

 were more regular. The yolk had considerably diminished, 

 and thread-like processes projected here and there from its 

 margin. Only a few red chromatophores existed on the 

 minute vesicular yolk-sac. The black corpuscles seemed to 

 form a band along the margins of the body superiorly and 

 interiorly. 



On the 27th June the colour under a lens was brick-red, 

 from the branching of both red and black chromatophores. 

 The eyes were somewhat darker and the yolk had still further 

 diminished. 



