664 ANATOMY OF THE MUZZLE OP OBSimOIiHYyCHUS, 



which we cannot but i-egard as ahiiost entirely hypothetical since 

 they are certainly absent from the (presumably) better preserved 

 specimens in our possession. 



The simpUcity and clearness of semidiagrammatic delineation 

 characterise other of Mr. Poulton's drawings than those which 

 are by him entitled " semidiagrammatic." This is of little import- 

 ance so long as the structural features are correctly given. But 

 in his important figure 1 (really semidiagrammatic) upon which 

 he lai-gely relies for illustration of the general features of the 

 push-rod, it is plain, both from his own descriptions and from his 

 figure 4 (see also our fig. 4*), that he has omitted, in each of 

 the three rods shown, a?i entire layer of cells (second layer of 

 imbricated cells). If, in our attempt by photomicrography to 

 avoid as far as possible errors such as these — arising no doubt 

 from a laudaljle desii'e for clearness and definiteness, — we have 

 incurred the reproach of making public, obscure and comparatively 

 uninstructive photomicrographic illustrations, we may at least 

 plead that these latter could not easily convey any erroneous 

 structural hypotheses. 



We shall now proceed to state the results of our continued 

 investigations into the structure both of the push-rods and of the 

 sweat-ducts. 



I. The Push-rods. 



With the fresh material recently secured we have in part 

 devoted ourselves to the obtaining of satisfactory silver impreg- 

 nations of the nervous elements of the skin of the muzzle by the 

 use of the rapid Golgi method and to obtaining the methyl-blue 

 reaction with the same structures by a modification of Ehrlich's 

 method. With both methods of procedure we have achieved a 

 fair measure of success. In order also to compare with our former 

 highly successful gold preparations by Freud's method with 

 bichromate tissue, we have followed Ranvier's formic-gold method 

 for fresh tissue and have again procured very good results. 



The further investigations we have thus been enabled to make 

 into the anatomy of the push-rods in view of Poulton's late 



* Macleay Mem. Vol. loc. cit. 



