426 



SCIENCE. 



[N. S. Vol. VII. No. 169. 



covering the position of the closed eye. The 

 various cases tested by the method described 

 led to the conclusion ' that the closed eye 

 follows the open eye to a certain extent, and to 

 a certain extent obeys its own tendencies of 

 relaxation.' These facts, together with the 

 changes in accommodation pointed out, may be 

 made use of to explain some of the differences 

 between ordinary vision and vision with a 

 single eye, as, for example, the fact that an 

 object seen with one eye looks farther away 

 and smaller. 



Chas. H. Judd. 

 TVesleyan University. 



SCTENTIFIC LITERATURE. 

 Lehrbuch der vergleichenden mikroskopischen 

 Anatomie der Wirbellhiere. Von Dr. med 

 Albert Oppel. Zweiter Theil. Sohlund 

 und Darm. Jena, Gustav Fischer. 1897. 

 Price, 20 Marks. 



The second part of Professor Oppel's store- 

 house of facts is a valuable addition to our 

 literature on microscopic anatomy and is to be 

 classed with books of the calibre of Minot's 

 Embryology. It is a handsome volume of 682 

 pages, 343 text figures and four lithographic 

 plates. In addition to an exhaustive review of 

 all the literature on the oesophagus and intes- 

 tines (the stomach having been considered in 

 the first volume), it gives a list of the scientific 

 names of the animals, a classification of the 

 vertebrates, a list of all the references, an index 

 of the authors and a complete index of its con- 

 tents. All in all, it is a hand book of the 

 microscopic anatomy of the oesophagus and 

 intestines. 



In general he states that the intestinal canal 

 is always composed -of the following layers : 



1. A mucosa covered with a layer of epithe- 

 lium. This, in turn, is divided into the true 

 mucosa and the submucosa, between which 

 there is usually a muscularis mucosae, and less 

 frequently an additional layer lying upon the 

 muscularis mucosse, the stratum compactum. 



2. A muscularis, usually composed of an 

 inner circular and an outer longitudinal layer. 



3. An adventitia, often poorly developed, 

 and towards the body cavity (ccelom) covered 

 with a layer of flat endothelium, the serosa. 



or muscle layers. 



After giving the above very general classifi- 

 cation of the layers in order to adapt them to 

 all the classes of vertebrates, Oppel states that 

 the following are the important layers : 



1. Epithelium. 



2. Tunica propria of the mucosa. 



3. Stratum compactum. 



4. Muscularis mucosae, circular and longi- 

 tudinal layers. 



5. Submucosa. 



6. Circular muscle, 



7. Longitudinal muscle, 



8. Subserosa. 



9. Serosa. 



These layers iu turn are bound together by 

 glands growing in from the epithelium, blood- 

 vessels, lymphatics and nerves. In general, 

 under the above headings he discusses the 

 whole subject, each time giving the variations 

 corresponding to the order of the families of 

 the vertebrates. Throughout the work most 

 extensive use is made of the literature and 

 nearly all of the figures are borrowed, but 

 they have been carefully redrawn. 



After the chapter on the cesophagus the 

 epithelium of the intestine is taken up (pp. 160- 

 232), giving the history of its discovery, and 

 its appearance in animals from amphioxus to 

 man. Then are discussed such subjects as the 

 striated border, cell membrane, intercellular 

 bridges, relation of the epithelial cells to the 

 connective tissues, basement membrane, regen- 

 eration and goblet cells. Under intercellular 

 bridges it is interesting to note that sufiicient 

 data have been collected to state that the bridges 

 do exist, and it is prophesied that future inves- 

 tigation will fully corroborate this view. 



The regeneration of the epithelial cell is dis- 

 cussed under the heading 'Bizzozero's theory.' 

 Bizzozero's observation is that the epithelial 

 cells at the bases of Lieberkiihn's crypts are 

 constantly dividing to re-establish the cells of 

 the villi. In order to do this the cells must be 

 shifting constantly from the bases of the crypts 

 towards the tips of the villi. This, according to 

 Oppel, is very unlike regeneration in other or- 

 gans, and, if true, will lead to the conclusion 

 that the crypts are not glands, but only grow- 

 ing points for the cells covering the villi. It 

 appears to us unfortunate that Oppel does 



