566 JOHN BEERY HAYCKAFT. 



Heematoxylin Solution. 



. C Ammonia alum, 3 grammes ; o (" Pure hsematoxylin, 3 grammes ; 

 ' l Distilled water, 100 c.e. ' C Absolute alcohol, 16 c.c. 



Mix A and B, keep in diffuse daylight for two weeks, and dilute with 20 

 volumes of distilled water. 



On looking down into the connective tissue with a power of 

 three or four hundred diameters, the modified nerve-fibres are 

 seen branching in all directions. On deeper focussing the 

 lower cells of the epithelium are seen from below. Their out- 

 lines are in most situations fairly well seen, and their nuclei 

 should be stained with the haematoxyliu. 



In these preparations the nuclei frequently shrink within 

 the nuclear cavities, appearing as dark blue granular masses 

 (b, fig. 4) ; but in most cases they fill the nuclear cavity, and 

 their chromatin filaments can clearly be made out. The 

 greater number of cells are devoid of any nerves, but here 

 and there nerve-fibres may be seen branching again and again 

 in the connective tissue, and sending their finest ramifications 

 to the nuclei of the epidermic cells. These are what appear to 

 be definite sensitive spots where alone the nerves terminate. 

 These spots are of variable size, so small as to correspond to 

 a space occupied by only a dozen cells, or so large as to occupy 

 two or three fields of the microscope. I should say that some 

 twenty or thirty of these " spots " might be found on one 

 square inch of a costal scute. Between these spots the epithe- 

 lium presents, as already observed, nothing very remarkable, 

 but within the spot the appearance is very striking. 



The non-medullated fibres deeply stained with the logwood 

 divide again and again, sending, in many cases, hundreds of 

 fibres to the epithelial cells. Fig. 3 represents a sector of one 

 of these spots carefully drawn from a specimen. At the circum- 

 ference (b) the fibres terminate in only a few of the epithelial 

 cells, but towards the centre all or nearly all of the cells 

 receive fibres. The outlines of the cells are not well marked, 

 the fibres at first sight appearing to terminate in little round 

 blue masses, which are in realitv the nuclei of the cells. 



