28 Dtt. KLEIN. 



clear nuclear body. It is evidently not rash to look upon 

 these flat branched structures which we have just described 

 as the surface appearance of the external wall which was 

 previously mentioned in the profile view as containing 

 oblong rod-shaped nuclei ; indeed, we need the less hesitate 

 to do so since Boll (33) has demonstrated that what is called 

 memhrana 'propria in glands in general, is not structureless 

 membrane, but a network of flat-branched cells, which are 

 bent in a basket-like manner to correspond with the alveoli of 

 the glands. 



If we now follow the nervous filaments of the fourth 

 order, which penetrate the wall of the gland, we may see 

 them simply making their way between the gland-cells, bifur- 

 cating in their course and uniting with each other in a reti- 

 form manner. This, indeed, is all that we are in a position 

 to say with certainty ; on account of their plane being identical 

 with that of the intercellular cement of the gland-cells, 

 they elude all attempts to trace them further Avith certainty. 

 As far, however, as we can follow with certainty between the 

 gland-cells their independent filaments, distinguished as they 

 are by their colour and granular swellings, we cannot demon- 

 strate a connection on their part with any of the cellular 

 structures of the gland. 



Up to this point Ave have treated of the division of the 

 finer nerves in the tissue of tlie nictitating membrane, and 

 of their relation to the epithelium, blood-vessels, and glands. 

 There is still another subject which we have to discuss before 

 leaving the nictitating membrane, and that is the cellular 

 structures. On a membrane which has been successfully 

 coloured with chloride of gold, and from Avhich most of the 

 epithelium of both surfaces has been removed, we may 

 recognise, if we employ higher powers (8, 9, 10). large flat 

 and, as a Avhole, oblong structures situated in the middle 

 layers of the membrane, and consisting of protoplasm fur- 

 nished with granules, in some places finer, in other places 

 coarser. In the interior of this protoplasm also lies a sharply 

 contoured, oblong nucleus which is sometimes smooth and 

 sometimes crenate, in which again there are always to 

 be observed one or two large shining nucleoli. At times 

 there are besides these other finer granules. What is easily 

 determined in all these structures is this, that their body is 

 prolonged into a number of longer or shorter processes of 

 various thickness, which are mostly branched, so that the fur- 

 ther they are removed from the body of the cell the more 

 attenuated they become, and which unite with those of the 

 neighbouring cells. See PI. II, fig. 7. 



