THE PRIMITIVE PORES OF POLYODON SPATHULA 



BY 



HERBERT D. KISTLER, B.S., M.D. 



{From the Anatomical Laboratory, St. Louis University.) 

 With Plate XVIII. 



This work was undertaken with the view of determining the 

 character and significance of these remarkably numerous organs, 

 about which there is very Httle in the literature. The nomen- 

 clature of CoLLiNGE (i) has been used in designating these struc- 

 tures as primitive pores. 



The material used was obtained from fishermen, who frequently 

 catch the fish on set lines. Those studied in this case were from 

 80 cm. to 90 cm. long and weighed from twenty-six kilos to thirty- 

 three kilos. They were brought to the laboratory alive and the 

 desired structures placed immediately in various fixing solutions. 

 For the purpose of general histological study picric-sulphuric- 

 acetic acid, corrosive sublimate-acetic acid, and 10 per cent, for- 

 malin were used. These tissues were embedded in paraffin and 

 stained with Delafield's haematoxylin, Heidenhain's iron 

 haematoxylin and acid fuchsin. For the study of the distribution 

 of medullated nerves, i per cent, osmic acid gave the best results. 

 To bring out the neuro-fibrillae and their terminations a num- 

 ber of methods were employed, among which were Apathy's 

 aftergilding gold chloride method and the Golgi method after 

 both formalin and potassium bichromate-osmic fixation. 



The method which gave the most precise differentiation of the 

 neuro-fibrillae was the following: The pieces of bill, head and 

 gill-flaps were placed in 10 per cent, formalin for two weeks. They 

 were then transferred to 10 per cent, formic acid for twenty to 

 thirty minutes, then to i per cent, gold chloride for fifteen to twenty 

 minutes Following this they were placed in a 2 per cent, formic 

 acid solution, in the dark, for twenty-four to forty-eight hours, or 

 until the tissue acquired a rich purple color when viewed with the 



