362 Prof. Wood-Mason and Mr. Alcock. On the [Mar. 



He observed that there was to be found in the uterine cavity 

 little fluid, generally milky, more rarely glairy, and sometimes bl 

 which, on evaporation, yielded crystals of common salt, and a 

 little animal matter composed chiefly of albumen ;" and he specula 1 

 on the possibility of this uterine secretion being nutritive, 

 negatived, however, the supposition that the embryo in utero co 

 take in food by the mouth, and inclined, finally, to the opinion tha 

 the embryo increases by absorption, partly through the general 

 surface of the body and partly through the branchial filaments. 



Sir Everard Home ( 4 Phil. Trans.,' 1810, p. 208), in a paper on the 

 " Mode of Breeding of the Oviviviparous Shark," which is quoted by 

 Joh. Muller, described the naked-eye anatomy of the oviduct of 

 Acanthias vulgaris, the jelly and which fills that part of its cavity 

 and which functions as a uterus in this Selachian. He states that when 

 the young one is completely formed the yolk remains attached to the 

 belly by a long cord of blood-vessels, and that the young one in thai 

 state " swims " in the uterine jelly. The jelly he regards as a secre- 

 tion of the oviduct. 



Home further quotes the observation of Dr. Patrick Russell, that a 

 Shark caught in lat. 70 N. had the oviducts distended with yonng 

 ones, each with the yolk-sac attached ; the young ones swimming in 

 a " white gelatinous liquid, thicker than the liquor amnios of Quad 

 rupeds." Home supposed that the function of the jelly was to aerate 

 the foetal blood. 



To sum up, we find that in Spinax niger, Scymnus lichia, Acanthiat 

 vulgaris, Trygon pastinaca, Torpedo oculata (and also in Myliobatit 

 noctula and Centrina salviani, according to Trois, in a paper in the 

 ' Atti del Istituto Veneto,' vol. 2, which we have unfortunately been 

 unable to obtain), special glandular villi have been observed on the 

 uterine mucosa, which villi have in some cases been supposed to bear, 

 either to the egg or to the developing embryo, some relation of 

 support or nutrition other than that of furnishing an egg-case, or of 

 assisting in the formation of a vascular connexion (yolk-sac placenta) 

 between the embryo and the mother. 



In Scymnus lichia, on the one hand, it seems certain, from Miiller's 

 researches, that the villi secrete a fluid which nourishes the embryo 

 through the medium of the yolk-sac ; while in Torpedo, on the other 

 hand, it is certain that, at least in the later stages, the seci 

 reaches the embryo in some less indirect manner, and the question 

 has actually been asked whether it is ingested by the embryo. 



In corroborating the opinion as to the function of the villi ot 

 Selachian uterine mucosa, we are able to bring evidence of a case in 

 which the nutritive secretion is actually conveyed into the pharynx 

 of the embryo. 



Following on this, and because the term " villus," in its connexions 



