278 Journal of Applied Microscopy. 



ANIMAL BIOLOGY. 



Agnes M. Claypole. 



Separates of papers and books on animal biology should be sent for review to 



Agnes M. Claypole, Sage College, 



Ithaca, N. Y. 



CURRENT LITERATURE. 



A 4.1. a^ t T^- 1 • J T-i , Gold chloride has come to be con- 



Apathy, Stefan. Die leitende Elemente der 



Nerven Systems. Mitteilungen aus der sidered as of especial value in Studying 

 Zoologischen Station zuNeapel, 12:4. the finer points of neurological anat- 



omy. As all the possibilities of this reagent have not yet been determined, any 

 new details regarding its use are of interest. The Mitteilungen aus der 

 Zoologischen Station zu Neapel, gives the method as applied by Dr. Stefan 

 Apathy in his study of the relations between nerve fibers and nerve cells. Apathy 

 was fourteen years in perfecting the method, which, with the characteristic 

 altruism of the scientist, he gives to the public. 



The salt used was aurum chloratum flavum (AuCl^H + 4H2O ?) in prefer- 

 ence to aurum chloratum fuscum (AuClg + ^HgO ?), and there are two methods 

 of application, one in which the gold chloride is used on fresh tissue, and 

 another in which the material is first fixed in some killing reagent. The two 

 methods give opposite results. In the first case the cytoplasm is stained, 

 but the nucleus is left almost colorless, primitive contractile fibers are very pale, 

 and interfibrillar substance is almost as dark as the cytoplasm of the muscle cell. 

 The whole nerve, as distinguished from the myelin sheath, is more or less dark 

 reddish-violet, so that the axis cylinder of the vertebrate nerve, for example, 

 would be clearly differentiated, and the peripheral branchings could be followed. 

 Gold chloride applied after fixation gives a very clear nuclear stain, the chromatic 

 as well as the achromatic elements being affected, so that in karyokinetic figures 

 the chromosomes, the spindle fibers, and the centrosome are stained with 

 different intensities, the chromosomes and the nucleolus of resting nuclei being 

 most deeply colored. The cytoplasm is paler, but plasmic structures are sharply 

 stained. Thus the plasma of the muscle cell is pale, but the contractile primi- 

 tive fibrils are bright cherry seal. 



Nerve fibers are stained intensely black. Inter and peri-fibrillar substances 

 take a very light stain, which differs from the other so that the neural substance 

 is very clearly differentiated. Gold chloride may be used equally well on tissue 

 from marine, fresh water, or land animals. 



In the first method, the fresh material is placed in the dark in a one per 

 cent, solution of gold chloride crystals in distilled water, for at least two hours, or, 

 in the case of thin membranes, over night. Then without washing it is changed 

 to a one per cent, solution of formic acid and exposed to the light in such a way 

 that the rays of light may reach it on all sides, and left for at least six or eight 

 hours. After the first hour, when the fluid has become dark, and therefore 

 absorbs considerable light, the formic acid should be renewed, care being taken 

 to move the object as little as possible. When the reaction is completed, the 



