148 



TURTOX NEWS 



feathers. The latter grow from deep 

 follicles. The essential part of a feather 

 is a cornified epithelium, and the pig- 

 ment is all formed in the epithelial 

 cells. While it is growing the feather has 

 a core of mesodermal tissue, with blood 

 vessels and loose fibrous tissue. There 

 are no general skin glands. The preen 

 gland is a special oil gland of epidermal 

 origin, being composed of numerous secre- 

 tory tubules lined with a many layered 

 epithelium. 



Man. The epidermis is many cells thick, 

 and the cells grade from cuboidal in the 

 basal layer to squamous on the surface. 

 The surface is cornified, the thickness 

 of the horny layer being much greater on 

 palm and sole than on the general body 

 surface. The dermis is a complex organ, 

 consisting basically of a dense white 

 fibrous tissue. It is supplied with abun- 

 dant blood vessels and nerves and contains 

 sweat glands, oil glands and hair follicles. 

 These are all epidermal structures. The 

 sweat glands are branched tubular serous 

 glands lined by a low columnar epi- 

 thelium. The oil glands are also branched 

 tubular glands, but the tubules are filled 

 with rounded or hexagonal cells with a 

 foamy cytoplasm. They are located chiefly 

 near the hair follicles. Hair, like the 

 feathers of birds and the scales of reptiles, 

 is primarily ectodermal. The shaft of the 

 hair is made up of keratinized epithelial 

 cells. The root contains a mesodermal 

 papilla of blood vessels and fibrous tissue, 

 but this does not enter into finished hair. 

 Pigment is scarce in white skin. In negro 

 skin the epidermal cells contain abundant 

 pigment granules, and there are scattered 

 chromatophores in the sub-epidermal 

 tissue. The pigment of hair is of the 

 epidermal-granular type. 



HARVEY M. SMITH. 



(The next article in this series will 

 appear in the May issuse of TTTRTOX 

 NEWS.) 



Gorilla 



We recently secured a splendid series 

 of gorilla skulls and skeletons many of 

 which have already been cleaned and 

 mounted. Included in the series are skulls 

 and complete skeletons of male, female 

 and young gorillas. One particularly in- 

 teresting preparation is an infant skele- 

 ton mounted in liquid with the natural 

 cartilages intact. Prices and complete 

 descriptions will be mailed upon request. 



Now Ready 



BIOLOGICAL FIELD WORK 



The first copies of the new 1934 edition 

 of Biological Field Work were mailed on 

 March twelfth and since that time several 

 hundred copies have been sent to those 

 requesting them. 



This year's edition of this book includes, 

 not only a completely revised and up-to- 

 date directory of summer camps and 

 biological stations and other features of 

 former editions, but also two entirely new 

 features. These are, first, a table showing 

 methods of collecting and preserving ani- 

 mals used in the laboratory and second 

 photographs of many of the biological 

 stations described in the book. 



Collection and Preservation Table, the 

 first of its kind. For many years the 

 General Biological Supply House has 

 freely given information on the methods 

 used in the Turtox laboratories in the 

 preparation of the specimens which we 

 supply to schools for dissection purposes. 

 Several of our Service Leaflets also deal 

 with this subject. However, the Collec- 

 tion and Preservation Table found in the 

 1934 edition of Biological Field Work 

 represents our first attempt to condense 

 the information into a two-page table pro- 

 viding the essential information. Obvi- 

 ously the table cannot include all of the 

 animal forms used in the laboratory, but 

 it includes twenty-four different forms 

 and gives information as to where found, 

 special collection devices, how to kill, 

 fixative and preservative for each. The 

 table covers the more commonly used 

 animals and includes representatives from 

 practically all of the animal phyla, be- 

 ginning with the sponges and ending with 

 mammals. The information is so arranged 

 that questions concerning habitat, killing 

 methods, preservatives, etc., can be in- 

 stantly answered by referring to the 

 proper columns in the table. 



Photographs through courtesy of Sta- 

 tion Directors. We are deeply grateful to 

 the directors of the summer camps and 

 biological stations for their fine coopera- 

 tion in supplying information and photo- 

 graphs for this book. We feel that the 

 photographs have added a great deal of 

 interest to the directory section of the 

 book. 



Copies still available. Although a 

 limited number of copies were printed 

 this year, we still have several hundred 

 on hand which will be distributed free of 

 charge to those requesting them. Write 

 for your copy now. A postal card will 

 bring it to you by return mail. 



