416 ANATOMICAL AND PATHOLOGICAL OBSERVATIONS. 



cells. Between the nucleus and the cell-wall is a light-brown 

 fluid, with one or two oil-globules floating in it. 



The vesicular caeca in the testicle of Sgualus cornubicus 

 contain nucleated cells, which ultimately exhibit in their 

 interior bundles of spermatozoa. 



The generative caeca of Echiurus mdgaris (Lamark) contain 

 cells full of minute spermatozoa. 



Aplysia punctata secretes from the edge and internal 

 surface of its mantle a quantity of purple fluid. The secreting 

 surface of the mantle consists of an arrangement of spherical 

 nucleated cells. These cells are distended with a dark purple 

 matter. 



The edge and internal surface of the mantle of Janthina 

 fragilis (Lamark), the animal which supplied the Tyrian dye, 

 secretes a deep bluish purple fluid. The secreting surface 

 consists of a layer of nucleated cells, distended with a dark 

 purple matter. 



If an ultimate acinus of the mammary gland of the bitch 

 be examined during lactation, it is seen to contain a mass of 

 nucleated cells. These cells are generally ovoidal, and rather 

 transparent. Between the nucleus and the cell-wall of each 

 a quantity of fluid is contained, and in this fluid float one, 

 two, three, or more oil-like globules, exactly resembling those 

 of the milk. 



In addition to the series of examples already given, 1 

 might adduce many others to prove that secretion is a function 

 of the nucleated cell. Some secretions, indeed, are so trans- 

 parent and colourless, as to render ocular proof of their 

 original formation within cells impossible ; and we are not 

 yet in possession of chemical tests sufficiently delicate for the 

 detection of such minute quantities. The examples I have 

 selected, however, show that the most important and most 

 striking secretions are formed in this manner. The proof of 

 the universality of the fact, in reference to the glandular 



