[ 379 ] 

 LVI. Proceedings of Learned Societies. 



ROYAL SOCIETY. 



[Continued from p. 311.] 



Jan. 15, \ PAPER was read, entitled, " On the Development of 

 1852. -£*- the Ductless Glands of the Chick." By Henry Gray, 

 Demonstrator of Anatomy at St. George's Hospital. Communicated 

 hy W. Bowman, Esq., F.R.S. 



In this paper the author has demonstrated the evolution of the 

 spleen, supra-renal and thyroid glands, and the tissues of which 

 each is composed, in order to show the place that may be assigned 

 to each in a classification of the glands. 



The spleen is shown to arise between the 4th and 5th days, in a 

 fold of membrane which connects the intestinal canal to the spine 

 (the " intestinal lamina"), as a small whitish mass of blastema, per- 

 fectly distinct from both the stomach and pancreas. This fold 

 serves to retain it and the pancreas in connection with the intestine. 

 This separation of the spleen from the pancreas is more distinct at 

 an early period of its evolution than later, as the increased growth 

 of both organs causes them to approximate more closely, but not 

 more intimately with one another ; hence probably the statement of 

 Arnold, that the spleen arises from the pancreas. With the increase 

 in the growth of the organ and the surrounding parts, it gradually 

 attains the position that it occupies in the full-grown bird, in more 

 immediate proximity with the stomach ; hence probably the state- 

 ment of Bischoff, that it arises from the stomach . Later, when its 

 vessels are formed, the membrane in which it was developed is 

 almost completely absorbed. 



The author then considers the development of the tissues of the 

 spleen, which clearly establishes, not only the glandular nature of the 

 organ itself, but the great similarity it bears with the supra-renal 

 and thyroid glands. 



The external capsule and the trabecular tissue of the spleen are 

 both developed between the 8th and 9th days, the former in the 

 form of a thin membrane composed of nucleated fibres, the latter 

 consisting of similar fibres, which intersect the organ at first sparingly, 

 and afterwards in greater quantity. The development of the blood- 

 vessels and the blood are next examined. The former are shown to 

 arise in the organ independent of those which are exterior to it. 

 The development of the blood-globules is shown to arise from the 

 blastema of the organ at the earliest period of its evolution, and 

 continue their formation until its connection with the general vas- 

 cular system is effected, at which period their development ceases. 

 No destruction of the blood-globules could ever be observed. These 

 observations disprove the two existing opinions of the use of the 

 spleen, as the blood-discs are not formed there (excepting during its 

 early development), as stated by (icrlachand Schaffner; nor arc they 

 destroyed there, as stated by Kolliker and Ecker. 



The development of the pulp tissue is next examined. At an 



