CHONDRIOSOMES IN CELLS OF FISH-EMBRYOS 473 



These filaments are of various lengths and are either located 

 close to the nucleus or extending into the processes (figs. 5, 6c 

 and 7a). In Fundulus, the niesenchyme-cells surrounding the 

 anterior part of the digestive tract (i.e., those situated close to 

 the dorsal wall of the pharynx and in the branchial arches) 

 become, during the fourth day, loaded with large granules. 

 These granules stain intensively with acid fuchsin, crystall- 

 violett and iron-haematoxylin. The same cells contain also long 

 chondrioconts (fig. 3). Altogether, they build up a very dense 

 layer of tissue. 



Blood-corpuscles contain a few long filaments (figs. 1 and 4a), 

 often sharply curved, and usually many shorter ones, in the 

 shape of loops or of small circles, accumulated in one or two 

 heaps. As soon as haemoglobin is formed in the red corpuscles, 

 no chondriosomes are visible — a peculiarity I had noted before 

 in the chick-embryo ('10, 2). No attempt, however, was made 

 with the modification of Benda's method, which Shipley ('15) 

 has devised for the special purpose of staining chondriosomes in 

 the red corpuscles. 



Besides ordinary leucocytes, the body-cavities and the tissue- 

 clefts in Fundulus hold a peculiar kind of large wandering-cell, - 

 in which the chondriosomes are represented by very thin threads, 

 mostly accumulated near the nucleus in dense masses (fig. 4c). 



The cells of the Wolffian ducts show at their basis an accumu- 

 lation of chondriosomes: rods, loops and circles. Long chon- 

 drioconts emerge from this accumulation and reach the oppo- 

 site pole, where some can be seen to bend and run backward 

 toward the basis of the cell (fig. 5). Chondriosomes have al- 

 ready been described in the kidney-cells of the adult fish by 

 Policard and Mawas ('06, '09) and by Regaud ('08). 



In Fundulus embryos three days old, I found a striking dif- 

 ference between the disposition of the chondriosomes in the 

 cells of the anterior and of the posterior part of the digestive 

 tube. In the posterior part (fig. 6a), numerous chondriosomes 

 are accumulated below the nucleus, which is, so to speak, im- 



* Whether these cells have any relation to the four kinds of wandering cells 

 described by Stockard ('15) in the yolk-sac of Fundulus seems rather doubtful. 



