THE PINEAL BODY 



123 



also complicated in the chorioid plexus, a commissura habenularis, 

 an epiphysis with a fairly well marked recessus pinealis and a 

 posterior commissure. Herrick 177 in 1891 described the epi- 

 physis in ophidia as a compact, somewhat rounded or oval 

 body whose interior consists of a connective tissue network with 

 many blood vessels, thus giving it the appearance of a branched, 

 tubular gland. Studnicka 386 maintains that nothing definite is 

 known of the significance of the epiphysis in snakes. Its un- 

 usually rich capillary blood supply speaks in favor of the sup- 

 position that the organ is a gland which contributes its product 

 to the blood stream. 



In Chelonia the pineal organ is only in a rudimentary condi- 

 tion and develops in these forms an epiphysis or corpus pineale. 

 Just as in ophidians, the end-vesicle and the stalk of the pineal 

 organ appear not to be laid down in anlage, or if it does occur in 

 the early stages of the development, it soon disappears, leaving 

 only the proximal portion to represent the pineal organ in these 

 forms. Neither in chelonia nor jn ophidia is there any evidence 

 of an anterior epiphysis, that is to say, a parietal eye. The 

 first description of turtles was given by Bojanus 36 in 1819. 

 Tiedemann 395 also mentioned the epiphysis in turtles, but prob- 

 ably mistook the chorioid plexus for that structure. Voeltz- 

 kow 410 in 1903, describing the embryology of Chelone imbricata, 

 mentions the first appearance of the epiphysis as a simple evagi- 

 nation. Secondarily, a stalk develops between the pineal organ 

 and the roof of the interbrain, so that, according to Voeltzkow, 

 the epiphysis in Chelone imbricata separates itself entirely from 

 the roof-plate. The pineal region in chelonia presents the 

 usual features, namely, a large paraphysis which forms an 

 unusually extensive sac. The end of this sac lies directly over 

 the epiphysis. The velum transversum and dorsal sac are 

 incorporated in the chorioid plexus. There is a fairly well 

 marked commissura habenularis, the epiphysis in its usual 

 chelonial form, and also the posterior commissure. The form 

 of the epiphysis in the turtle is oval or ovoid; it lies close to 

 the roof-plate. The surface, as Herrick 177 has shown in 1891, 

 is uneven and may indicate :-, process of lobulation. Many 



