136 J. DUESBERG 



swell. The extent to which the ground substance is affected is 

 well illustrated by the difference in size exhibited by the cells 

 represented in figures 10 and 11, both in exactly the same stage 

 of evolution, the first from material fixed in Benda's fluid, the 

 second from material treated with Regaud's. Thus, cells which 

 normally float freely in the cystic cavity are made to conglomer- 

 ate and stick together. The chondriosomes are also sw^ollen, and 

 the chromosomes are transformed into an undecipherable clump. 

 In contrast to this, the last-named bodies are well preserved in 

 Benda's material, an appearance which confirms that swelling in 

 Regaud's rather than shrinking in Benda's fluid is responsible 

 for the differences between the two sets of preparations. 



The testicle of Fundulus is at the time of spawning a rather 

 voluminous organ formed by a considerable number of tubular 

 cysts in which spermatogenesis proceeds from the periphery 

 towards the hilus.^ The excretory system of the gland consists 

 of a number of ducts lined with cubic or cylindric epithelium. 

 In the distal part of these ducts the cells (fig. 1) contain, besides 

 secretion-granules, a large number of chondriosomes. These are 

 mostly long chondrioconts running along the nucleus in a direc- 

 tion perpendicular to the basis of the cell and intertwining at 

 both poles of the nucleus. This disposition reminds one some- 

 what of the structure of the cells of the tubuli contorti (Heiden- 

 hain's rods) or of the salivary ducts (Pfliiger's rods). The inner 

 part of the cell is often free of chondriosomes and irregularly 

 delimited, an appearance which may be due to the action of the 

 fixing fluid. 



In the cells lining the proximal part of the excretory ducts, 

 the chondriosomes are all replaced by granules of pigment. 

 This recalls an observation made by Prenant ('11) on the skin 

 and cornea of the frog. Prenant found that the cells of both 

 layers in the skin contain mitochondria and pigment-granules. 

 In the upper layer the granules of pigment are located near the 

 surface, the mitochondria in the lower part of the cell, w^hile in 

 the deeper layer mitochondria and pigment-granules are mixed 



' Degenerating cells are, as in other testicles and especially in invertebrates, 

 b}' no means infrequent in Fundulus. 



