Mr. Ferrall on certain Structures in the Orbit. 168 



of plants. The author describes each of the tissues of this class at 

 length, and shows that the various modifications presented by the 

 vascular system with which each is in contact, have the sole object 

 of enabling a large quantity of blood to approach and circulate 

 slowly around them. He also points out, in connexion with this 

 subject, the remarkable vital properties which are possessed by these 

 non-vascular tissues. 



In concluding this paper, the author states that his object has been 

 to establish as a law in animal physiology, that tissues are capable 

 of being nourished, and of increasing in size, without the presence 

 of blood-vessels within their substance. He shows the analogy 

 which is presented between the extra- vascular animal and the extra- 

 vascular vegetable tissues. He expresses a hope that the application 

 to surgery of the above law, with reference to the prolongation of 

 blood-vessels into the extra- vascular tissues during disease, and to 

 pathology in the investigation of the nature of morbid structures, 

 particularly of those classes which contain no blood-vessels, will be 

 not devoid of interest, and will be productive of some advantage. 



The Society then adjourned over the Whitsun recess, to meet 

 again on the 10th of June. 



June 10. — The following papers were read, viz. — 



1. " Magnetic-term Observations made at Milan, on the 21st and 

 22nd of April, 1841." Communicated by Professor Carlini, For. 

 Memb. R.S. 



2. " Register of Tidal Observations made at Prince of Wales's 

 Island, in July, August and September, 1840." 



3. " Register of Tidal Observations made at Singapore in July, 

 August and September, 1840." 



These two papers were presented by the Directors of the East 

 India Company, and communicated by P. M. Roget, M.D., Sec. R.S # 



4. " On the Anatomy and Physiology of certain structures in the 

 Orbit, not previously described." By J. M. Ferrall, Esq., M.R.I. A. 

 Communicated by Sir Benjamin C. Brodie, Bart., F.R.S. 



The author describes a distinct fibrous tunic, which he terms the 

 tunica vaginalis oculi, continuous with the tarsal cartilages and 

 ligaments in front, and extending backwards to the bottom, or apex 

 of the orbit ; thus completely insulating the globe of the eye, and 

 keeping it apart from the muscles which move it. The eye-ball is 

 connected with this fibrous investment by a cellular tissue, so lax 

 and delicate as to permit an easy and gliding motion between them. 

 The use which the author assigns to this tunic is that of protecting 

 the eye-ball from the pressure of its muscles while they are in ac- 

 tion. This tunic is perforated at its circumference, and a few lines 

 posterior to its anterior margin, by six openings, through which the 

 tendons of the muscles emerge in passing to their insertions, and 

 over which, as overpullies, they play in their course. A consequence 

 of this structure is that the recti muscles become capable of giving 

 rotatory motions to the eye without occasioning its retraction within 

 the orbit, and without exerting injurious pressure on that organ. In 

 those animals which are provided with a proper retractor muscle, 



M 2 



