2 50 THE SALAMANDER 



maculosa and Siredon pisciformis) 'quergestreift, meistens spindel- 

 formig, mit excentrischen grossen Kernen'. Finally Greil (1903) 

 completed our knowledge of the contractile portion of the lymphatic 

 system by describing the central lymph heart, within the truncus 

 arteriosus, dorsal to the aortic arches. 



An excellent detailed study of the caudal lymph hearts and of the 

 caudal lymph vessels was made by Favaro in 1906, while in 19 12 

 Hoyer and Udziela undertook an investigation of the lymphatics of 

 the larva. Their work is very thorough, and is based on direct obser- 

 vation by dissection of injected larvae as well as from serial sections 

 of both injected and uninjected specimens. The condition they 

 describe for the larvae needs but little amendment to make it applic- 

 able to the adult, the chief points of difference being the considerable 

 extension of the jugular sinuses and the comparative diminution of 

 the dorsal and ventral longitudinal vessels. 



2. Technique. 



The present investigation was carried out on animals that had 

 been killed with chloroform and injected immediately after death 

 with a semi-gelatinous mass made up as follows : 



An appropriate quantity of best white gelatine is allowed to soak 

 in a good excess of water for about twelve hours (overnight). The 

 excess water is then drained off and the gelatine melted in the water 

 it has absorbed. The resulting mass is referred to below as 'stock 

 gelatine'. The injection mass consists of — 

 60 gm. stock gelatine (melted) 



6 gm. potassium iodide 

 60 cc. pure glycerine 

 240 cc. sat. soln. of prussian blue in water. 

 This mass is liquid slightly above room temperature, but 'sets' to 

 about the consistency of the white of an egg. It flows freely, and the 

 prussian blue does not precipitate in the cannula, and, what is more 

 important where the larger sinuses are concerned, is freely mobile 

 without the injected mass breaking up or rupturing the walls of the 

 vessel. The 'setting' is a delayed action so that cold apparatus may 

 conveniently be used. It may be hastened by immersing the animal, 

 after injection, in formalin. Gravity pressure of about 150 cm. of 

 water was used for the injection, and, the point of the fine glass 

 cannula having been inserted under the skin of the palm of one hand, 

 the skin of the other palm and the soles of the feet were pricked with 

 a needle, and the extreme tip of the tail was cut off. When the injec- 

 tion mass dripped more or less freely from all these four points 



