TRANSACTIONS OP THE SECTIONS. lid 



condition has disappeared, we find that the contents have assumed the form of a 

 roundish or oval embryo, richly ciliated on its external surface, and with a large 

 central cavity. When liberated from the external membrane of the ovum, which 

 still confines it, it swims actively through the surrounding water. As development 

 proceeds, we find this ciliated body to present an anterior opening, through which 

 an unciliated hernia-like sac is capable of being protruded by a process of evagina- 

 tion ; and there is evidence to support the opinion that this protrusible non-ciliated 

 portion has been separated from the inner surface of the ciliated portion by a kind 

 of unlining. In the interior of the protrusible portion, the polypid is developed in 

 a manner which appears altogether similar to that by which new polypids are 

 produced by gemmation from the walls of the endocystal cavity of the adult. The 

 protrusible or non-ciliated portion remains for a time incapable of complete evagina- 

 tion, the posterior part of it being retained in a permanently invaginated state, by 

 bands which pass from it to the opposed surface of the ciliated portion in a manner 

 exactly similar to that by which the permanently invaginated part of the endocyst 

 in the adult is retained in its place by the parieto-vaginal muscles. As develop- 

 ment continues, these bands disappear, and the invagination with which they were 

 connected becoming obliterated, the non -ciliated portion becomes directly continuous 

 with the ciliated, and incapable of being any longer withdrawn within it. The 

 cilia now disappear, and the entire sac becomes enveloped in an ectocyst to consti- 

 tute the cell of the adult polyzoon. The subsequent changes are produced by the 

 gemmation of new polypids. 



The testis is developed in the form of an irregular roundish mass upon the funi- 

 culus, and frequently co-exists with statoblasts. It is composed of spherical cells, 

 each of which contains within it numerous "vesicles of evolution." The visible 

 contents of the vesicles of evolution are at first confined to a well-defined spherical 

 nucleus, and this is afterwards transformed into a spermatozoal filament, which 

 subsequently escapes by the rupture of the containing cells. The escaped sperma- 

 tozoa in Alcyonella present distinct, though not very active unduiatory motions. 

 They are simple filaments of uniform diameter, and destitute of capitulum. 



On the Law of Molecular Elaboration in Organized Bodies. 

 By Professor J. Hughes Bennett, 3I.D,, of Edinburgh. 



When the Association met in Edinburgh, the author pointed out to the Physiolo- 

 gical Sub-section, — 1st, how molecules are being continually formed in the body from 

 the union of oil and albumen, from the results of endosmose and exosmose, and 

 from various chemical combinations ; 2ndly, certain facts with regard to the peculiar 

 movements of these bodies — the molecular motions of Brown ; and 3rdly, how they 

 unite to form nuclei, fibres and membranes directly, independently of the agencj'' of 

 cell formation. He also pointed out that the process of degeneration was exactly 

 inverse to that of formation, and that the last as well as the first histological form 

 was the molecular. 



Subsequent research as to the behaviour of these molecules induced him now to 

 put forth the following law, viz. that the formations and transformations of the 

 various textures of the body not only talce their point of departure from molecules, hut 

 arc brought about by successive buildings up and breakings down of masses of molecules. 



By the term molecule or granule, the author did not mean a cell or nucleus, but 

 those smaller particles which are only distinguishable optically under high powers 

 by exhibiting a bright or dark centre, and a dark or bright border, according to the 

 focal point in which they are viewed. Organic molecules consist of a mixture of 

 some proteine compound with oil. 



He then referred to various well-known facts with a view of demonstrating that 

 ultimate form and composition were arrived at by a succession of formations and 

 disintegrations, and that when a new arrangement of parts took place this was 

 eflfected through the agency of molecules. He described, — 1st, the mode of develop- 

 ment of Ascaris mystax as detailed by Nelson ; 2ndly, that of the mammalian ovum 

 as described by Barry and Bischoff ; 3rdly, the mode of development in uni-cellular 

 plants and animals ; 4thly, the transformations of insects ; 5thly, the formation of 



