OBSERVATIONS ON STRUCTURE OF CELLS AND NUCLEI, 139 



— at any rate in the quiescent state — ■'' mucous cells/' i. e. glassy 

 transparent cells containing mucus. Lavclowsky^i whose work 

 on the anatomy and physiology of the salivary glands is distin- 

 guished by a great number of important observations, fully 

 establishes this in showing that in carnivorous animals both the 

 orbital and submaxillary glands are purely mucous glands. The 

 submaxillary gland of man, however, differs in so far from that 

 of the dog that it is a compound gland, including mucous and 

 true salivary gland (Boll, Lavdowsky), and not merely a mucous 

 gland, as stated by Henle.~ 



The cells lining the lumen of the gland tubes (so-called 

 alveoli) are in the submaxillary gland of dog, as is well known, 

 the central or mucous cells of Heidenhain, and outside these we find 

 the "crescents'^ of Gianuzni, of which Heidenhain has demonstrated 

 that they consist of a group of granular or protoplasmic cells. As 

 regards tlie former, viz. the central or mucous cells, Heidenhain^ 

 mentions that their substance is delicately striated. Ewald^ also 

 mentions a delicate striation of the mucous cells, " as though a 

 perfectly transparent substance was traversed by numerous ex- 

 tremely fine fibrils," and Lavdowsky states that the cells in the 

 quiescent gland contain, besides mucus, traces of protoplasm in 

 the shape of an exceedingly delicate network next the nucleus 

 which, as is well known, lies in that stage more or less compressed 

 close to the wall of the gland-tube. 



Heidenhain^ has asserted that during prolonged secretion the 

 mucous-cells are destroyed, and replaced by new cells formed out 

 of the " crescents," which new cells at first are ^' albuminous cells" 

 (Asp.) ?". e. consist of granular protoplasm like the cells of the 

 "crescents," but which are determined to become again trans- 

 formed into " mucous-cells." In this he is supported by BoU,^ 

 who mentions the same for the submaxillary gland, especially of 

 guinea pig. 



The condition of exhaustion is, according to Heidenhain and 

 Boll, characterised by the replacing of the transparent large mu- 

 cous cells with parietal compressed nucleus, by " granular " 

 smaller cells with a spherical nucleus placed more or less cen- 

 trally. That the gland cells possess a diflPerent aspect in the two 

 conditions has been confirmed by Ewald, Pfliiger and others ; 

 but Heidenhain's explanation of this fact has been contradicted 



1 'Arcliiv f. mikr. Anatom.,' Baud xiii, p. 287. 



- ' Systematisclie Anatomie, Eingeweidelehre,' 1S62, p. 133. 



^ 'Ber. d. K. Sachs, Ges. d. Wiss.' Leipzig, 1865. 



* ' Beitiage z. Histol. mid Physiol., d. Speicheld d. llundes,' Berlin, 1870; 

 mentioned also bv Pfliiger in bis article ou " Salivarv Glands," in Strieker's 

 ' Handbook.' 



5 L. c, pp. 17 and 28. 



c ' Archiv f. Mikr. Anatom.,' Baud v, p. 334, 



