PINEAL AND PITUITARY BODIES OF THE BRAIN. 23 
that the subneural gland in the Tunicata now performs 
the same function. 
From the time of Savigny (1816) up to Julin’s investi- 
gations the dorsal tubercle in Ascidians had been regarded 
as a sense-organ, for the purpose of testing the quality 
of the water entering the branchial sac (Pl. II., fig. 2). 
Julin, however, insisted upon its non-nervous nature, and 
regarded it as being merely the opening of the duct from 
the hypophysis into the front of the pharynx. 
In a short paper, published in July, 1883,* I, arguing 
mainly from the very complicated condition of the dorsal 
tubercle in many Ascidians, suggested that possibly this 
organ may be both the aperture of the hypophysial gland 
and also a sense-organ of a gustatory or olfactory nature. 
I pointed out that if the hypophysis cerebri was, as EH. van 
Beneden and Julin think, a renal organ in the anterior 
part of the body of the primitive Chordata, its ducts— 
supposing it to be formed of several pairs of nephridia— 
would originally open on the sides of the body (Pl. IL., 
fig. 3, left side), and might have then become implicated 
in the sinking in of the epiblast to form the atrial 
involutions (Pl. II., fig. 3, right side), and so would come 
to open into the peribranchial cavity (a condition found in 
some Ascidians). The dorsal tubercle again may have 
been a sense-organ in the same primitive Chordata, placed 
at or near the dorsal edge of the mouth opening, which 
afterwards changed its position, perhaps along with the 
involution of the epiblast which forms the branchial 
siphon (stomodzum), so as to reach the dorsal edge of the 
buccal cavity (Pl. IL., fig. 4, h). I would regard then the 
connection between the duct, or one of the ducts, of the 
subneural gland and the dorsal tubercle as being secondary. 
* Nature, vol. xxviii., p. 284, 
