1908.] 



ANATOMY OF A FROG. 



35 



muscles. It is mainly at least by the anterior lialf or three- 

 quarters of each lymph-heart that it is fixed to the integument 

 by these muscular strands, which have to be cut through in order 

 to free the organ. When it is thus freed it is seen to be of about 

 the same shape as an acorn (without its cup) and divisible into 

 two regions, an anterior and posterior, which are however not 

 very sharply marked off from each other. 



Text-fig. 11. 



d.. 



1, 



\-Ohl.int. 



M. 



Left lympli-heart of Breviceps. 



, b. Extrinsic muscles of heart (S.). G. Tip of coccyx. Ohl.int. Obliquus 

 intenins cut otf short on both sides, o.d. Oviduct. 



The anterior part of each lymph-heart (as is shown in text-fig. 12, 

 p. 36), which represents one of these structures completely freed 

 from its attachment to the integument, is of very dense muscular 

 structure, and in consequence quite smooth. The posterior part 

 (not half) of the heart, however, is of a basket-work conformation, 

 strands — varying in breadth, but always broadish — of muscular 

 fibres crossing each other at right angles. The bands of fibres 

 which run in a longitudinal direction are ultimately lost in the 

 regular even and muscular walls of the anterior part of the lymph- 

 heart. The cross-running bands are also seen in the figure to be 

 also gradually diflierentiated from it. The interspaces between these 

 bands are considerable, and possibly permit of the free entrance 



