322 William E. Kellieott 



Material and Methods 



The material from which these data were drawn was secured at the 

 Laboratory of the Woods Hole Station of the Bureau of Fisheries.^ 

 The data were collected with quite another purpose in view, but the 

 present questions have arisen and may be considered at this time. 



The data are given in full in Table III, pp. 343-350. 



The determinations were made with the accuracy usual in statistical 

 work; the weighings were made to 0.01 gram. The organs determined 

 were the brain, heart, rectal gland, pancreas, spleen, liver and gonad. 

 These parts were removed within one-half hour after the fish ceased 

 to react to touch, and in practically every case the heart was still beating 

 when it and the other organs were removed for weighing. The attach- 

 ments of the viscera were cut through along the surfaces of the organs 

 and the organs rolled gently in a towel until the blood was expressed. 

 The brain was sectioned from the cord in situ, in a transverse plane ex- 

 tending just along the posterior tip of the cerebellum. Anteriorly the 

 olfactory tracts were cut off along the contours of the hemispheres. The 

 infundibulum and pituitary body were included, but the cranial nerve 

 roots were removed along the surface of the brain and the outer mem- 

 branes removed. This of course does not give a complete brain, but the 

 limits chosen seemed to give the best compromise between completeness 

 of l)rain and rapidity of removal. This last factor might be one of 

 considerable importance on account of the rapidity with which the weight 

 of the brain changes after death. In the heart no satisfactory landmark 

 could be found along which to section the sinus venosus from the veins 

 nor from the auricle: consequently the entire venous end of the heart 

 was removed along the auriculo-ventricular groove which is very definite. 

 Anteriorly the heart was sectioned at the junction of the conus and 

 truncus. What is referred to as "heart" includes therefore only the 

 ventricle and conus arteriosus. These parts make up by far the greatest 

 part of the weight of the heart and at the same time are the chief 

 functional elements in the fish. The rectal gland was removed as nearly 

 as possible along the line where its duct commenced. 



In preparing the plates the weight of each organ in each individual 

 was recorded separately. The curves were derived from these records 



'I take pleasure in acknowledging my indebtedness to Commissioner George 

 M. Bowers, of the Bureau, and to Director Francis B. Sumner, of the Labora- 

 tory, for the privileges of a research room and a large share of the dogfish 

 material collected during the seasons of 1906 and 1907. 



