Maech 25, 1898.] 



SCIENCE. 



427 



not see his way clear to accept Bizzozero's 

 theory of the regeneration of the cells covering 

 the villi, as it is the only plausible explanation 

 of it. It does not seem to us that a shifting of 

 the cells from the crypts to the villi necessarily 

 proves that the crypts are not glands, for it is 

 by no means shown that the function of the 

 cells covering the villi is only to absorb. It 

 may also be to secrete. The large number of 

 goblet cells would appear to indicate this. More- 

 over, similar instances corroborative of Bizzo- 

 zero's theory are not wanting, as, for instance, 

 in the central nervous system and in the epi- 

 dermis, and until it is proved to be incorrect it 

 seems to us that it is well to retain the theory. 



The mucosa proper is the most complex por- 

 tion of the intestine, as the folds, villi, and villi 

 upon folds, are only modifications of a simpler 

 membrane. In the mucosa we have all of the 

 characteristics of a lymph gland, extending from 

 the muscularis mucosae into the folds and villi. 

 Between the bases of the villi and the muscula- 

 ris mucosae, the crypts, when present, are 

 lodged. The connective-tissue frame-work of 

 the mucosa has been shown to be composed of 

 fibers, neither white fibrous nor yellow elastic, 

 which are constantly anastomosing to form a 

 reticulum identical with that of lymph nodules. 

 Siegfried has recently shown that they are com- 

 posed of a body rich in sulphur and phosphorus, 

 which he has called 'reticulin.' Oppel gives a 

 good discussion of this tissue and its importance. 

 Below the crypts the lymphatic tissue is ar- 

 ranged in a layer known as the stratum granu- 

 losum. 



Between the stratum granulosum and the 

 muscularis mucosae there is an additional 

 hyaline membrane. This layer had been ob- 

 served a number of times in the stomach and 

 intestine of various animals and was isolated 

 and discussed by Mall as the stratum flbrosum. 

 Oppel objects to this name, as there had been a 

 difference of opinion regarding its constitution, 

 and substitutes for it the name stratum com- 

 pactum. Since the appearance of Oppel' s 

 book, however, Spalteholz has shown con- 

 clusively that this layer is really composed of 

 white fibrous tissue, a.id, therefore, the name 

 stratum fibrosum is still appropriate. It is to 

 be regretted that Spalteholz' s paper appeared 



too late to be used by Oppel, for the introduction 

 of new terms has a tendency to add confusion 

 to the subject. 



The description of Brunner's glands, the 

 lymphatic vessels and nodules, the blood- 

 vessels and nerves is extensive and complete, 

 but it is of such a nature that it cannot be given 

 in a brief review. 



The above shows the extent and some of the 

 features of the book. It is a mine of facts ar- 

 ranged in such a manner that anything in it 

 can be easily found. If the work were more 

 critical it would be of much greater value. 

 But as it stands it is a great addition to our 

 literature and will be welcomed by all stu- 

 dents of anatomy. Franklin P. Mall. 



Whittaher's Mechanical Engineer'' s Pocket-book. 



By Philip E. Bjorling. London, Whitta- 



ker & Co.; New York, The Macmillan Co. 



1898. 32mo. Pp. 377. Illustrations. Price, 



$1.75. 



This is a ' pocket-book ' of the now standard 

 form and page, and including the usual compi- 

 lation of tables and data for use in the design of 

 machinery and works of engineering. It is 

 neatly put up and well bound, with good paper 

 and clear type of larger size than the micro- 

 scopic print often seen in such books, vexing 

 the eye and trying the patience of the reader. 

 The first section of the book is devoted to hy- 

 draulics and water-wheels, and is exceptionally 

 extensive for- a compilation of this size. The 

 section on steam-engines includes modern forms, 

 and gives the proportions of the later construc- 

 tions. The empirical but standard rules of 

 construction are given, as customarily employed 

 by British designers, and good tables of hyper- 

 bolic logarithms and of mean pressures are 

 added. Proportions of details of machine-con- 

 struction are given very fully, no space being 

 given up to references. The usual and always 

 necessary numerical tables conclude the woi'k. 



R. H. T. 



The Entropy- Temperature Analysis of Steam-En- 

 gine Efficiencies. Prepared by Sidney A. 

 Eeevb, M.E. New York, Progressive Age 

 Co. 1897. 8vo. Pp. 20, with large folded 

 diagram. 

 Since the publication of the now famous 



