• OBSERVATIONS ON STRUCTURE OF CELLS AND NUCLEI. 167 



intracellular network has a somewhat different arrangement ; in 

 the elongated cells it also assumes an elongated arrangement 

 parallel to the long axis of the cell, so that the cell-substance 

 appears longitudinally striated. 



This appearance belongs to the same kind as the one I de- 

 scribed in the first chapter, viz. the alteration of shape and 

 arrangement of epithelial cells, owing to a change of the mem- 

 brane on which the epithelium is situated. 



8. The Epithelial Cells of the Testis. 



In this paragraph I wish to describe chiefly the structure of 

 the nuclei of the epithelial cells of the seminal tubules and of the 

 so-called parenchymatous cells between them (tubules). 



{a) If we examine a section through testis of full grown cat, 

 dog or guinea-pig, hardened in our mixture of chromic acid and 

 methylated spirit, or in pure methylated spirit, we see that 

 the nuclei of the polygonal, or more or less rounded cells 

 which in several layers line the seminal tubules, possess a 

 great many minute rods connected into a network. At first 

 sight the nucleus appears coarsely and uniformly granular, 

 but on careful inspection we ascertain that these coarse gran- 

 ules are the sectional view of shorter or longer rods. The 

 network formed by them possesses on this account a some- 

 what different appearance from that mentioned on several pre- 

 ceding occasions, and I refer the reader to figure 15, a and b, 

 of Plate VII, where I have represented these appearances. The 

 nuclei of all except some of the most external cells, i.e. those 

 next the membrana ])ropria, are spherical and possess the network 

 of the short rods mentioned just now. The nuclei of the last- 

 named cells are, however, oval, and contain the more uniform 

 network of fibrils mentioned of other nuclei. 



The same character of a network of short rods may be observed 

 in the nuclei of the multinuclear large cells present in some of 

 the seminal tubes of cat and dog (v. La Valette). There is 

 nowhere any sign of a nucleolus. 



The intranuclear network comes out with great distinctness in 

 preparations of testis treated with a 5 per cent, solution of 

 chromate of ammonia, and subsequent staining in picro-carmine 

 in the manner described in my first paper of stomach of newt.^ 

 I should especially recommend for class-demonstration of a beavi- 

 tiful intranuclear network to use the testicle of full-grown newt, 

 and to prepare it after the method with 5 per cent, solution of 

 chromate of ammonia and subsequent staining in picro-carmine. 



1 L. c, p. 319. 



