18 CHARLES R. STOCKARD 



Figure 3 illustrates a more or less similar condition seen from 

 a dorsal view. A small portion of the heart slightly projects 

 beyond the anterior end of the head. If this egg were placed 

 in lateral view, as was the case in figure 2, then the heart would 

 be seen to show a similar condition, since it also was stretched 

 out into a long narrow tube. 



Figure 4 represents a very defective embryo. Specimens 

 similar to this occur in great numbers in the stronger alcohol 

 solutions. The bodies are very short since the descent of the 

 germ ring over the yolk sphere is slow and at times incomplete, 

 and the tail end of the embryo is often bifid or split giving a 

 condition of cauda-bifida. At the anterior end, the upper 

 right side of the figure, is shown the distended pericardial vesicle, 

 and at the posterior end another large distended vesicle is in 

 most cases the Kupffer's vesicle, but in some instances this is 

 possibly distended spaces in the yolk mass just below the Kupf- 

 fer's vesicle. These two sacs or spaces at the opposite ends of 

 the body seem to be the places in which the non-circulating 

 plasma most often accumulates to a great degree, in fact the 

 accumulation of plasma is the actual cause of the exagerated 

 condition of the spaces. In the individual illustrated by figure 

 4 the chromatophores are extremely small, but have arranged 

 themselves to some extend so that they are very abundantly 

 accumulated around the periphery of the Kupffer's vesicle while 

 others have collected in the region of the pericardium. In the 

 lateral yolk regions there are scarcely any pigmented cells present. 

 All of these chromatophores, however, are small and contracted 

 with very few processes of any extent. 



• In Fundulus embryos there are readily seen two distinct types 

 of chromatophores. Tlie one is a large dense perfectly black body 

 with short broad processes. While the second is of a reddish color 

 at first small and without processes, but later sending out very 

 long graceful radiations which grow at the expense of the central 

 mass until finally the whole chromatophore assume a moss- 

 hke branched structure, figure 6 shows both types well expanded. 



Loeb ('93) at one time pointed out that these chromatophores 

 migrate to the blood vessel walls and thus map the circulation 



