486 Cambridge Philosophical Society. 



several which Professor Fisher intends to bring forward, the general 

 object of which may be thus expressed : — 



Researches on certain forms of disease, considered in their con- 

 nexion with the process of formation, the growth and maintenance, 

 and the decline of the human frame. 



The tendency which the human ceconomy has to accomplish the 

 scheme of its organic existence, is the vital law by which the author 

 has been directed in these researches. Deriving his method from an 

 idea of Galen, Professor Fisher distinguishes in an organ two pro- 

 cesses, the plastic and the functional. Under the first he comprises 

 the formation, the growth, and maintenance of an organ, as well as 

 the alterations of structure, normal or anormal, which it may pre- 

 sent. Under the second, those acts of an organ by which it effects 

 results which have reference to the ceconomy. 



The physiological portion of Professor Fisher's communication 

 consisted of an account of some embryological researches he had 

 made on the development of the spinal ganglia, in order to throw 

 light on the anomalous conditions which some of them present in 

 Spina bifida, when that disease is limited to the lower region of the 

 spinal column*. Before stating the result of these researches, it 

 may not be inappropriate to mention, that those anomalous con- 

 ditions consist in a coalescence of the last lumbar with the first 

 sacral ganglion, or in a coalescence of some of the sacral ganglia 

 with each other f. In some instances a comparatively strong band 

 is found to pass from the fourth to the fifth lumbar ganglion J. 



Finding no mention made of the development of the spinal 

 ganglia by the physiologists whose works Professor Fisher con- 

 sulted, he was induced to make researches on the subject, of which 

 the following statement comprises the general results : — 



That the white, rounded or pyriform bodies which are situated on 

 the side of the furrow which occupies the site of the future spinal 

 cord of the embryon constitutes the rudiments of the spinal or 

 intervertebral • ganglia § . 



* In every case of Spina bifida which the author has met with affecting 

 the upper part of the spinal column, it was accompanied by a defective 

 formation of the head. 



f The author has not met with any instance in which this coalescence 

 did not exist. He has now examined sixteen cases. In one case the sub- 

 ject presented a club-foot, on the same side as that on which the two first 

 sacral ganglia were united. He could not recognise any trace of the anterior 

 roots on the united ganglia, but unfortunately the thigh was so lacerated 

 as not to enable him to ascertain with any degree of security whether any 

 part of the nervous or muscular system of the limb was deficient or not. 

 In the same case the fourth sacral ganglia on each side were united into 

 one mass, which was supplied by a single artery. In this case, as indeed 

 in all others which Professor Fisher has observed, the lumbar and sacral 

 nerves presented, as they emerged from their respective foramina, a na- 

 tural appearance. The sacral plexus always seemed to be duly formed. 



X The author at first thought this band might be a vessel, but careful 

 dissection convinced him that it was continuous with the sheath of the 

 ganglia with which it was connected. Its internal structure presented a 

 granular appearance. 



§ Professor Fisher, at the commencement of these researches, was im- 



