I40 A. C. EYCLESHYMER AND J. M. WILSON. 



mass of the cells being filled with a protoplasmic reticulum. 

 They may probably be regarded as modified mucous cells." 

 In regard to its function they say : " It does not appear prob- 

 able that the disc has a true sucking action. It is unprovided 

 with muscular elements, and there appears to be no mechanism 

 by which it could act as a sucking organ. We must suppose, 

 therefore, that its adhesive power depends upon the capacity of 

 the cells composing its papillae to pour out a sticky secretion." 



Von Kupfer ('93) has described the development of the head 

 in Acipenser basing his studies on median sagittal sections. He 

 derives the adhesive organ from the inner layer of the ectoderm 

 and states that it arises in close connection with the hypophysis. 

 It is at first single but becomes paired by a groove on the median 

 line. Each of these disks divides again, forming four papillae. 

 These four papillae develop into the four barbels of the adult fish. 



In regard to his derivation of the adhesive organs from the 

 ectoderm we may say : (1) Kupfer's work is based on median 

 sagittal sections and such sections are not those best adapted to 

 trace out the development of a paired organ like the adhesive 

 organs. (2) He has not described the earliest stages. His young- 

 est stage is an embryo forty-five hours after fertilization. (3) Even 

 by Kupfer's showing these organs are connected with the diges- 

 tive system, though it may be only through the hypophysis. 



Ehrenbaum ('94), as stated by Ziegler ('02, p. 157), gives a dif- 

 ferent origin for the adhesive organs in Acipenser. We translate 

 from Ziegler : " On the under side of the head in front of the 

 mouth one finds on each side two thickenings (Wulste) which 

 become the barbels. At this place we noticed in a somewhat 

 earlier stage a depression marked by a peculiar pigmentation ; 

 this corresponds to the sucking disk of Lepidostcus and Aniia." 

 How this is to be reconciled with von Kupfer's account of a com- 

 mon anlage for adhesive organs and hypophysis is not apparent 

 to us. Unfortunately Ehrenbaum's paper is not accessible and 

 we are not in position to give any further account of his work. 



On the whole then, while we have the high authority of von 

 Kupfer in favor of the view that in Acipenser the adhesive organs 

 take their origin from the ectoderm, in our opinion the subject 

 deserves further investigation as the proof is far from being 

 conclusive. 



