220 DR. W. K. F. WOODLAND ON THE 



the present paper, I wish to express my great indebtedness to the 

 Council of King's College, London, for generously allotting me 

 the sum of thirty pounds out of the Government grant to the 

 College for 1907 to defray a part of the expenses incurred by me 

 during my visit to the Naples Zoological Station in April of that 

 year. I wish also to express my indebtedness to the Naples 

 Zoological Station Table Committee of the British Association for 

 the occupancy of the table at Naples during the three weeks just 

 referred to, and to the staff of the Naples Zoological Station for 

 the large amount of trouble they took in supplying me with the 

 material I required in connection with this and other subjects. 

 Further, I wish to thank Professor A. Dendy, F.E..S., and 

 Professor S. J. Hickson, F.Pt.S., for kind recommendations in 

 connection with the above-mentioned grant and occupancy of the 

 Naples table respectively. Professor J. P. Hill, D.Sc, and Dr. G. 

 C. Chubb for recent friendly assistance, Mr. C. Tate Regan, M.A., 

 for kindly advising me in connection with the systematic nomen- 

 clature adopted in this paper (the nomenclature of Giinther's 

 Catalogue), and Mr. C. Biddulph, who has considerably lightened 

 the burden of preparing some hundreds of slides. Finally, I am 

 also much indebted to the Council of the Royal Microscopical 

 Society for kind permission to occupy their table at the Plymouth 

 Marine Biological Laboratory during a week in August, 1909. 



Part II. — A few Suggestions concerning the Physiology 

 OF the " Bed Bodies," 



It wasihy original intention to include in Part II. of this paper 

 a resume of our present knowledge of the physiology of the gas 

 bladder*, but although, with this end in view, I have become 

 thoroughly acquainted with the whole of the vast literature 

 dealing with the subject, yet other work prohibits me at present 

 from thus devoting the time necessary for the composition of 

 such a review. This being the case, I shall content myself with 

 providing an outline sketch of the chief views which have hitherto 

 been advanced to explain the mode of working of the "red bodies," 

 in order that the reader may be in a position to estimate the 

 value of the few additional suggestions I have to make. 



The several views which have been held concerning the origin 

 of the three t principal gases — oxygen, nitrogen and carbon 

 dioxide — contained in variable proportions in the gas-bladder 

 cavity, can be classified into two categories : (1) the view (first 

 attributed to Redi) that these gases are derived directly from the 

 atmosphere, and (2) the views (lineal descendants of Needham's 

 secretion theory %) that these gases are derived more or less 



* A recent account of the functions of the bladder will be found in Baglioni (18). 



t Argon is also stated to occur in the bladder. 



X It should be noted that authors in discussing the production of gas employ the 

 term " secrete " in a verj' loose manner, some thereby meaning a true process of 

 ■ secretion, such as that which occurs in the sebaceous gland (Nusbanm & Eeis, 

 e. ff.), others (Hiifner, Jaeger) merely meaning a process of pumping from the blood. 



