§ 3.223 EFFECTORS WITH MOVABLE PIGMENT GRANULES 89 



by fractionation in alcohol (Brown and Scudamorc, 1940); but 

 much greater elegance and precision in separating pure substances 

 from the extracts is now possible by paper electrophoresis (Knowles, 

 CarHsle and Dupont-Raabe, 1955). So far the substances cluted 



Connective injection 

 V y >< Intact 





Eyestalkless 



1 I 



i!Sk!i=gWjDJi£tion Sinus g land froctions 



Intact 



/ > 



'+ insol. 



/ Eyestalkless 



Eyestalkless"^® ^^Z" 



/ 



sol. 



(d) 



2 3 12 3 



Time, hr 



Fig. 3-15. Reactions of the red chromatophores of the fiddler crab, 

 Uca. id) The natural background response: the rising curve 

 (dotted line) shows the rate of change of red chromatophores 

 after a light-adapted specimen is transferred from a white to a 

 black background; the falling curve (full line) shows the converse 

 change from black to white, in constant illumination. All measure- 

 ments were made over the same time of day to avoid the influence 

 of diurnal rhythmic changes. (6) The response of intact and eye- 

 stalkless specimens from black backgrounds to injections of Uca~ 

 RED-DISPERSING HORMONE, URDH, from the sinus gland. Prompt 

 dispersal occurs in the eyestalkless specimen; the dark intact 

 specimen shows pallor first, presumably due to operative shock, 

 (c) The response of similar specimens to injections of an extract of 

 circumoesophageal connectives. The result indicates a short-lived 



action of t/ca-RED-CONCENTRATING HORMONE, URCH, but is 



ambiguous, {d) The responses of eyestalkless specimens to in- 

 jections of alcohol insoluble (above) and alcohol soluble (below) 

 fractions of a sinus gland extract, to show that the former contains 

 most of the dispersing hormone, URDH (all from Brown, 1950). 



