BY .7. T. WILSON AND C. .1. MARTIN. ()79 



In a recent paper | upon the anatomy of young specimens of 

 Echidna, Professor W. Newton Parker describes shortly the 

 developing sweat-glands in the skin of the snout of that animal, 

 and, pointing out their resemblance to those described by Poulton 

 in Ornithorhynchus, he expresses his dissent from the hypothesis 

 advanced ))y the latter writer to explain their peculiar structure. 

 Neither his description nor his figures appear to us to afford 

 sufficient ground for rejecting a theory which, although without 

 doubt antecedently improbable, is yet borne out by so many 

 striking correspondences in structui-e indicated by Prof. Poulton 

 and in the present paper. 



The developmental stages studied by Prof. Parker were proba])ly 

 much too late to afford conclusive evidence as to the real manner 

 of development of these structures. So, at least, an inspection of 

 his special figure of the sweat-gland and duct on Plate ii. would 

 indicate. The only specific reference we note to an earlier con- 

 dition, is the statement that " the lumen is not developed in the 

 young stages." 



EXPLANATION OF PLATES. 



Fig. \. — Vertical section of rod-organ, showing nervous arrangements, from 

 a preparation impregnated with silver by Golgi's rapid method 

 ( X 320 diams. ). At the base of the rod the axis-cylinders of the 

 nerve fibres show out strongly. These fibres have two destina- 

 tions (a) to the base of the rod where some join the small 

 Pacinian bodies and the remainder penetrate the rod-organ to be 

 continued up almost to the surface as the axial and peripheial 

 groups of axis-cylinders. (6) To the sides of the rod-organ, 

 where some enter the organ to take part in the formation of the 

 peripheral circular group of axis-cylinder processes, whilst others 

 pass up to the sides and tip of the papilla, where they enter the 

 epidermis. The axis-cylinder processes apparently end in tlie 

 superficial portion of the rod-organ, and are not demonstrated 



X P.Z.S. 1804, Part i. pp. 3-14, Plates i. 



