SECTIONAL TRANSACTIONS.— D. 365 



16. Prof. W. D. Henderson. — The Morphology and Development of the 



Hyomandibula in Fishes. 



The paper deals with the development of the hyomandibular cartilage in fishes. 

 The development has been studied in several specimens of each group, and a summary 

 of the facts as given in previous work has been made. The relation of the nerves, 

 blood-vessels, and muscles to the cartilage in the various groups has been traced. The 

 position of the articulatory facet on the walls of the otic capsule has been followed 

 in the various forms, as some of the newer views have been based mainly on this in 

 discussing the homology of the Hyomandibula. No trace of a double head has been 

 found in any of the specimens examined, so that there seems to be little support for 

 the view that the foramen for the R. hyomandibularis facialis is the result of the 

 fusion of two cartilages. The views of Allis, Schmalliausen, andde Beer are discussed 

 in relation to the points found in the specimens studied and also in connection with 

 the accounts given by previous workers. 



17. Mr. Gr. Leslie Purser. — On some interesting Morphological Features 



of Calamoichthys. 



(a) The dentition shows a significant intermediate condition between those with 

 many rows of functional teeth and those with but one. 



(6) The sharp change-over from an ectodermal to an endodermal type of epithelium 

 at the level of the glottis casts doubt upon the present-day view of the germ-layers 

 at the beginning of the alimentary canal. What is our basis upon which we decide 

 homology ? 



(c) The whole of the blood from the last gill-arch and part from the last but one 

 loasses directly to the lung of the same side. The structure of the wall of the latter 

 is confirmed to be respiratory. Asymmetry of the lungs, both as regards size and 

 relationship to one another, indicates that the left ono is really a diverticulum from 

 the originally median and single right. 



(d) The venous system exhibits at least one very important series of peculiarities : 

 there is a well-developed posterior vena cava, though its origin is farther back than 

 is usual ; and the posterior cardinal veins are very asymmetrical, as the left is reduced 

 to an azygos, while the right remains large and serves both sides of the body 

 posteriorly. 



18. Dr. D. Hutchinson. — Amoeba {Cinematograph film). 



Saturday, August 7. 



Excursion to Tring. 



Monday, August 9. 



19. Dr. G. D. Hale Carpenter. — Lecture on some of the Problems con- 



nected with Sleeping Sickness. 



Sleeping Sickness must not be confused with Encephalitis letkargica, or ' Sleepy 

 Sickness.' It is a disease of tropical Africa caused by a flagellate protozoon 

 {Trypanosoma) transferred by Tsetse flies of the muscid genus Qlossina. Several 

 closely allied forms of Trypanosoma found in animals and man cause ' fly disease ' of 

 cattle, or ' Nagana,' and Sleeping Sickness. One of the problems discussed is whether 

 T. brucei of ' Nagana ' is essentially the same as, and can become, T. garnbiense of 

 Sleeping Sickness, and whether T. rhodesiense, causing a more acute disease in man, 

 is derivable from brucei or/and garnbiense. Possibly the nature of these Trypanosomes 

 depends largely upon the mammalian host rather than upon the species of Glossina 

 transmitting them, but the method of transmission may have much to do with the 

 degree of virulence. 



Trypanosomes mechanically transmitted on the proboscis of Glossina seem more 

 virulent, while the developmental processes in Glossina whereby Trypanosomes are 

 injected in the salivary secretions seem to reduce virulence. 



An important problem is whether other insects than Glossina transmit Sleeping 

 Sickness. From the point of view of habitat there are two main t3'pes of Glossina, 



