TRANSACTIONS OF SECTION D. 811 



absence of any recent systematic investigation has led me to give some attention 

 to the same. 



Its important bearing upon general morphology may be grouped under three 

 headings : — 



(i.) The important modifications that its presence has effected in the cranial and 

 other bones of the skull. 



(ii.) The modifications in the cranial nerves. 



(iii.) The evidence of the evolution of a series of sensory organs. 



My investigations have been chiefly carried out upon Ganoids, the more important 

 results of which are summarised below. 



In Polypterits : — 



1. There is a complete absence of dendriform branches, and also of any openings 

 corresponding to primitive pores. In these two features it agrees with the more 

 highly specialised Ganoids. 



2. The connection of the operculo-mandibular branch with the main canal is 

 established contrary to the statements of Traquair, Allis, and Pollard, though not 

 in the manner figured by Wiedersheim. 



3. The presence of a canal traversing the series of lateral canal bones, and of 

 another running across the cheek-plate, also a rudimentary one in the preoper- 

 culum. 



4. The distinctness of the preoperculum hitherto considered as doubtful by both 

 Huxley and Traquair. 



In Lepidosteus : — 



1. The presence of a system of dendritic branches which, passing ofi'from the 

 main canal, anastomose and form a dense network, which resembles in many points 

 that found in the Selachia. 



2. The absence of any branching on the lateral canal. 



3. The presence of a preorbital commissure, not previously described as occur- 

 ring in the Ganoids, and a prenasal commissure. 



4. The distinctness of the preoperculum, termed by Parker interoperculum. 

 From further investigations, not yet completed, we may state that — 



1. The canal system in the Elasmobranchs approaches in many points the 

 condition found in the Selachoid Ganoids, both in the course of the canals, 

 branches, sensory organs, &c., and in the branching of the lateral canal and in the 

 distribution of the cranial nerves. 



2. It seems very probable that the numerous sensory organs that have been 

 described can be reduced to three or four, which are really only stages in the 

 evolution of a sense-capsule. 



4. On the Starch of the Chlorophyll-granule, and the Chemical Processes 

 involved in its Dissolution and Translocation. By Horace T. Brown, 

 F.B.S. 



Important advances have been made of late years in our knowledge of the 

 carbohydrates and of the transformations which some of them undergo when they 

 are acted upon by various enzymes or soluble ferments. The work described in 

 this paper was an attempt by the author and his colleague, Dr. G. H. Morris, to 

 apply the experience gained by a long acquaintance with the carbohydrates to the 

 elucidation of some of the metabolic processes at work in green leaves. 



They have been able to throw some new light upon the chemical and physio- 

 logical processes involved in the formation of autochthonous starch, the first visible 

 product of assimilation in the chloroplasts, have succeeded in explaining the mode 

 of dissolution of this starch within the plant cell, and have demonstrated the nature 

 of the wandering metabolites intermediate between the starch and the formation of 

 new tissue. Full details of most of the results and of the methods employed will be 

 found in the ' Journal of the Chemical Society,' 1893, p. 604. (See also ' Annals 

 of Botany,' vol. vii. p. 271.) 



It is possible to determine with great accuracy the starch of the chloroplasts of 

 the leaf by converting it (after extraction of the ready-formed leaf-sugars) into 



