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FREDERICK TILNEY AND LUTHER F. WARREN 



presents itself is a single evagination in front of the posterior 

 commissure. The further differentiation of the epiphysis is 

 given by Lieberkiihn 242 in Gallus and also in much more detail by 

 Mihalkovicz 274 in 1874 and 1877. According to the description 

 of the latter, the principal change from the original saccular 

 evagination in the roof-plate consists in the conversion of the 

 original sac into a folliculated structure which presents many 

 alveoliform cell groups as a result of the rapid proliferation in 

 the walls of the original saccular anlage. Henrichs ('96) 173 

 found that the follicles first developed as hollow buds in com- 

 munication with the main cavity of the original epiphyseal 

 anlage, Later these buds become branched and in this way a 

 rich follicular system is developed. 



Fig. 35 The epiphyseal complex in an embryo of Sterna hirundo. according to 

 Klinckowstroem,"1891. 



According to Henrichs, the paraphysis first appears as a solid 

 sprout and later acquires a lumen. Cameron 51 showed in the 

 chick that the epiphyseal anlage is a double outgrowth, the left 

 being the larger. These two evaginations ultimately coalesce. 

 Practically the same condition is observed in amphibia. Gar- 

 jano 144 makes the observation which in the main covers the con- 

 ditions observed in birds, namely, that as compared with the 

 lower vertebrates the pineal body is a profoundly altered organ 

 in birds and mammals. 



One of the authors in a recent work on the diencephalon re- 

 produces illustrations of reconstruction models which show the 

 development in the pineal region of Gallus gallus. The first 



