530 



R. A. SPAETH 



of the microscope immediately after decapitation and the mel- 

 anophores could then be seen to be expanding. The dorsal 

 and caudal fins proved to be the most favorable regions for ob- 

 serving this change although the method was far from satisfactory. 



3. Methods 



Following a suggestion of Biedermann and others who had 

 obtained excellent fixed preparations from the scales of fishes, 

 the attempt was made to observe the behavior of the living chro- 

 matophores in this way. Owing to particularly favorable topo- 

 graphical conditions the method proved quite satisfactory. The 

 details of the manipulation of the scales were as follows. 



A section through the skin of F. heteroclitus (parallel with 

 the chief axis of the body) shows the following relations : 



Superficial 

 Melanophores 



Epidermis □ 



Fig. A Diagrams of the scales in Fundulus. 1, position of the scales in a 

 cross-section of the skin; 2, single scale held by forceps; 3, side view of isolated 

 scale. 



The scales are so arranged that it is possible by inserting a 

 broad scalpel at the point x, to raise the scale, 1 , with its super- 

 ficial layer of chromatophores and epidermis, without injuring 

 or disturbing them in any way. The deeper melanophores 

 (shown as stellate bodies in the figure) remain behind in the proc- 



