280 THE AMERICAN MONTHLY [December, 



Hamamelis J'^irg-inica. showing peculiar structures called "'osteo- 

 selereid cells," found at the extremities of the fibi-o-vascular bundles, 

 and situated verticalh' to the leaf-surfaces, after reaching to the epi- 

 dermis. He concluded that they are functionally strengthening ele- 

 ments. They are very abundant in the leaves growing in the shade, 

 and wanting in those of firmer texture exposed to the sun light. 



o 



Brooklyn Medical Microscopical Society. 



September 4, j88g. — The twenty-fifth meeting was held at the 

 Hoagland Laboratory. The President, Dr. C. Heitzmann, read a paper 

 on '• The Litimate Structure of the Derma of the Skin." Dr. J. H. 

 Mennen read a paper on " Silver Images in Liflamed Cornea." 



Dr. Heitzmann said that, in reviewing the literature of this topic, 

 the essayist comes to the conclusion that a thorough knowledge of the 

 structure of the derma is as yet lacking. This tissue becomes intelli- 

 gible only through the knowledge of tendon, in which the bundles run 

 in a strictly parallel course, whereas in the derma, as in aponeuroses, 

 the bundles are interlacing. Transverse sections of the bundles show 

 interstices filled with medullary and delicate fibrous connective tissue ; 

 thev are rich in blood-vessels and nerves, and may be termed inter- 

 stices of the first order. Smaller groups of bundles are separated from 

 one another by groups of the second order, likewise holding smaller 

 blood-vessels. Between the larger bvmdles we find protoplasmic forma- 

 tions, all interconnected, and thus producing a network, strikingly 

 similar to that of a myxomatous connective tissue. These are the in- 

 terstices of the third oixler. The bundles themselves are split up, 

 though incompletely, into smaller ones by interstices of the fourth 

 order, holding thin layers of nucleated protoplasm, or elastic fibres. 

 The reticulum of protoplasm is continuous throughout the derma. In 

 longitudinal sections of bundles only the protoplasmic bodies, but no 

 lateral offshoots and no net-like arrangement thereof, can be seen. Dr. 

 Heitzmann then described the papillary layer of the derma, which 

 shows diflerence in structure according to age. In the new-born the 

 papillce are mainly protoplasmic in nature ; made up of delicate fibres 

 in the middle aged ; and in old age of a coarse fibrous tissue, freely in- 

 termixed with hvdropic protoplasmic bodies, thus causing the appear- 

 ance of a myxo-fibrous structure. All the bundles are traversed by an 

 extremely delicate reticulum of living matter, that can be brought to 

 view by treatment with alcohol, or by treatment with solutions of gold 

 chloride. The same reticulum is visible in specimens hardened in 

 solutions of chromic acid, immediately after mounting in glycerine. 

 As soon as the glycerine soaks into the tissue the reticulum disappears, 

 l^hese details can only be studied in specimens mounted in glycerine, 

 not in Canada balsam. 



October .?, i88g. — Dr. G. T. Kemp was elected a member, and Dr. 

 A. R. Robertson was proposed. A publication committee to decide 

 on the suitability of papers for publication was appointed, consisting 

 of the president, the secretary, and of Dr. Van Cott. 



After the transaction of the regular business, an address was given 

 by the president on the *.'• History of the Development of Enamel." 

 which was discussed by Drs. Eccles, Van Cott, and Heitzmann. 

 (From Brooklyn Medical Journal^ Nov.. 1SS9.) 



