1887.] Prof. Lockwood, Development of Pericardium, fyc. 273 



so as to superadd to the other E.M.Fs. in operation that due to the 

 mutual neutralisation of the acid and alkali. 



Palladium behaves precisely as gold, 52 parts of metal being dis- 

 solved per 108 of silver deposited ; local action sometimes causes in each 

 case excess of amount dissolved relatively to the current passing, the 

 opposite result to that observed with the silver cells above described. 



Of course, if more powerful oxidising agents are used than simple 

 aeration plates (such as platinum in sulphuric-chromic solution), the 

 action goes on in all such cases still more rapidly ; thus, for example, 

 Ave did not succeed in dissolving gold in dilute hydrochloric alone by 

 the use of an aeration plate simply ; but on replacing this by a 

 platinum plate immersed in sulphuric-chromic liquor connected by a 

 siphon with the dilute hydrochloric acid in which the gold was 

 immersed, chlorination of the gold was readily effected with the for- 

 mation in the first instance of aurous chloride, which rapidly broke up 

 into particles of spongy gold and auric chloride in solution. 



II. "The Early Development of the Pericardium, Diaphragm, 

 and Great Veins." By C. B. Lockwood, F.R.C.S., Huuterian 

 Professor of Anatomy in the Royal College of Surgeons of 

 England. Communicated by G. M. Humphry, F.R.S. 

 Received November 26, 1887. 



(Abstract.) 



The history of the development of the pericardium, diaphragm, and 

 great veins is traced by means of rabbit's embryos ranging from the 

 eighth to the seventeenth day of intrauterine life. 



The splanchnic origin of the two halves of the heart is briefly 

 illustrated, and each separate half is shown to project into the fore- 

 most end of the ccelom. The approximation of the halves of the 

 heart, and of the ccelom in which they are contained, and the forma- 

 tion of the mesocardium posterius and anterius, is next narrated. 

 The course of the omphalomesenteric veins to the heart along the 

 splanchnic wall of the ccelom is then traced, and those vessels are 

 shown to divide the ccelom into two parts, a 41 cardiac " and a " pleuro- 

 peritoneal." At the beginning of the ninth day the ccelom consists of 

 two halves which are some distance apart towards the tail end, but 

 converge towards the head to open behind the omphalomesenteric 

 veins, into the cardiac portions of the ccelom. To adopt a rough 

 comparison, the ccelom is, at the beginning of the ninth day, not 

 unlike a pair of trousers ; the cardiac portion would correspond to 

 that part of the trousers which receives the pelvis, whilst the hinder 

 parts of the ccelom. would correspond to the places for the legs. To 



