ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 139 



stances like starch, cellulose, and chitin ; and lie finds hints of it in 

 crystals of sulphur and of certain salts. In the forming crystal he also 

 ■finds radial lines proceeding from a centre, structurally like the radia- 

 tions of asters, both being due to a central pull exerted on an alveolar 

 structure. The work is of biological interest, not only in regard to the 

 point here noted, but for the discussion of the growth and polymorphism 

 of crystals, and the determination of the polymorphic form by external 

 conditions. 



Intestinal Mucous Membrane of Lota vulgaris.* — Profs. E. Yung 

 and 0. Fuhrmann note several important features in the intestine of 

 Lota. Comparing the distribution and structure of the elements of 

 the mucous membrane with those in ScyUium, they observe : — (1) The 

 buccal cavity contains distinctly fewer goblet-cells, while on the other 

 hand there are many " sacciform glands " which have no homologue in 

 the dog-fish. (2) The oesophagus has the same structure as the mouth. 

 It is completely devoid of ciliated epithelium, which is abundant in 

 ScyUium. This region is therefore not homologous in these two types 

 of fish. (3) The peptic glands of the stomach, uniformly tubular and 

 covered with pepsin-cells in the two types, are in Lota grouped into 

 sets of tubes opening into a common neck, while in ScyUium they are 

 simple and uniformly distributed in the mucous membrane. (4) The in- 

 testine is characterised by the presence of solid glands (glandes pleines) 

 over its whole extent. These glands are wanting in ScyUium. (5) The 

 stratified pavement epithelium resembles that of the buccal cavity. In 

 ScyUium it covers the whole of the cloacal region, while in Lota it is 

 limited to the edge of the anus. The last portion is thus not a cloaca, 

 and although separated from the middle part of the intestine by a valve, 

 yet undoubtedly belongs to it. 



Alimentary Canal of Birds.f — Dr. K. E. Schreiner has investigated 

 the minute characters of the oesophagus and stomach in a number of 

 families of birds. He finds that while in Larus the oesophageal glands 

 are of great simplicity, those of the duck are of a complicated character. 

 But he has been able to draw up a list of transitional forms, and finds 

 further that the difference between the glands of a reptile such as Testudo 

 and those of Larus, is hardly greater than that between Larus and the 

 duck. In regard to the stomach, the point of most interest is the 

 relation of the so-called " blind-sacs " of the proventriculus to the com- 

 pound glands of that region, and to the glands of the gizzard. As in 

 some birds (e.g. Uria, Tringa) the blind-sacs possess cells similar to 

 the secretory cells of the compound glands, the author concludes that 

 sacs and glands have a common origin in the simple tubular glands of 

 reptiles, and have both arisen as the result of a concentration of glandular 

 surface, rendered necessary by the division of the stomach into two 

 parts. This conclusion is supported by the comparative morphology 

 of the blind-sacs in the different families of birds. It is probable that 

 the glands of the gizzard are the homologues of these proventricular 

 blind-sacs, but this is not quite certain. This paper includes a descrip- 



* Arch. Zool. Exper., viii. (1900) pp. 333-51 (2 pis.). 



t Zeitschr. wiss. Zool., lxviii. (1900) pp. 481-581 (6 pis. and 11 figs.). 



