THE PARS BUCCAL1S OF THE HYPOPHYSIS 35 



intermedia solution. 19 Such a darkening clearly occurs, but an 

 attendant color change was unnoted by Atwell. These larvae 

 not only become darker, but they almost completely lose their 

 metallic iridescent appearance so characteristic of the picture 

 of albinism. As has been previously stated, this metallic effect 

 is due to the broad expansion of the xantholeucophores, an 

 effect which is displayed in its full beauty only because of the 

 deficiency in the epidermal melanin which characterizes albinos. 

 As might be surmised, then, these 'interference' cells have suf- 

 fered a great contraction, causing an almost entire loss of the 

 metallic-like albinous picture. Still another pigment change is 

 wrought by the pars intermedia solution. The epidermal melan- 

 ophores undergo expansion, ultimately assuming the expanded 

 condition typical of the normal animal under 'indifferent' en- 

 vironmental conditions. It is thus seen that the pars intermedia 

 emulsion can be described as bringing about a normal physio- 

 logical state in this atypical pigment system of the albino and, 

 as will be later pointed out, aids us in determining the endocrine 

 locus responsible for this pigmentary disturbance. 20 



When large albinous or normal specimens are placed in an 

 adrenalin 21 solution, serious respiratory and cardiovascular symp- 

 toms develop. The respiration becomes labored and slowed 

 and the heart beat decreases in rate. Although more active for 

 a few minutes, they soon become sluggish and rest in any posi- 

 tion. Gradually the gills become flushed and it is noted that 



19 Two strengths of pars intermedia solutions have been used. One made by 

 triturating 10 mg. of the dried substance in 100 cc. of water, the other by triturating 

 10 mg. in 300 cc. of water. Both solutions produced identical effects, but at a 

 different rate. The larvae would later succumb when left in the stronger solution 

 for a period of one and a half hours or longer. 



20 The immersion of larvae in Pituitrin (Parke, Davis & Co.) has produced 

 neither constant nor pronounced changes in the pigmentary system even when used 

 in strengths sufficient to cause the serious distress or death of the animals. An 

 emulsion of the posterior lobe (less the pars intermedia), even when used in strengths 

 greatly in excess of that employed with the pars intermedia, appears not to evoke 

 this reaction. Solutions of hypophysial colloid cause no pigmentary response. 



21 Adrenalin (Parke, Davis & Co.) has been employed in strengths of 1 to 20,000 

 to 1 to 80,000. The stronger solutions (1 to 20,000 and 1 to 40,000 in amounts of 

 10 to 40 cc. per animal) have been of more value, and attention is called only to 

 the responses evoked by these strengths. 



