Nr. 1] ANATOMICAL STUDIES ON ANELASMA AND SCALPELLUM 17 



may nevertheless fall in some specimens. At the transition to the 

 digestive intestine, the alimentary canal makes a sharp bend; the 

 ventral wall, i. e. that situated next to the cirri, forms as a rule a 

 right angle, whereas the opposite, dorsal wall shows a more equal 

 bend throughout the entire stomachal region. 



The digestive intestine is covered by a cylindrical 

 epithelium consisting of high cells. All the specimens investigated 

 had their intestine filled up by food, and the digestive cells showed 

 a vacuolised structure when stained withDELAFiELD — 'Van Giesson 

 (pl. IV, fig. 18). Staining with boraxcarmine-bleu de Lyon gives 

 another picture (pl. V, fig. 26) showing an almosit evemly granulated 

 protoplasm. The cells are lined with a cuticle exhibiting a finety 

 transversely striped structure («Ståbchensaum»). The nuclei of 

 the cells are rather large. It will be of interest here where dealing 

 with the nuclei of vividly functioning cells to mention their rela- 

 tion to different staining fluids. Treatment with Delafields, 

 haematoxyline demonstrates a great many chromatic granulations 

 in the nuclei (pl. IV, fig. 18); these granulations are also strongl} 7 

 coloured in boraxcarmine (pl. V, fig. 26). If, on the other hand, 

 we make use of Weigert's haematoxyline — iron ammonium sul- 

 phate, the nuclei only seem to contain one, or seldom two black- 

 coloured, rather small nucleoli. Excepting the glandular cells, 

 which will be treated farther below, the last picture is typical for all 

 somatic nuclei throughout the body of Scalpellum, and this seems, 

 moreover, to be the general result of the staining method nientioned 

 throughout the cirripeds, as previously indioated under the heading 

 of Anelasma. 



The digestive intestine also in Scalpellum lacks muscles. The 

 epithelium is furnished with a strongly prominent and rather thick 

 basal membrane (pl. V, fig. 26); herein it also differs from the 

 stomach, where the basal membrane is only feebly developed, and 

 from the oesophagus, where a basal membrane of the epithelium is 

 completely wanting. 



Through an abrupt constriction, the digestive intestine passes into 

 the short proctodæum; this last part of the alimentary canal 

 is richly provided with longitudinal f oldis of varying prominence. 

 The epithelium is rather low, al most cubical, and the boundaries of 

 the single cells are extremely difficult to demonstrate; the procto- 

 dæal epithelium forms the direct continuation of the thoracic 

 epithelium, and is, like this, lined with a homogeneous, struc- 

 tureless and chitinogene cuticle dispiaying a strong affinity to bleu 

 de Lyon. The cuticle of the proctodæum is a iittle thinmer than 

 the external thoracic cuticle. In its broad features, the proctodæum 

 is built like the oesophagus; the ring muscles, however, are in the 

 proctodæum coalesced to some degree, forming an almost con- 



