SCIENCE-GOSSIP. 



247 



Wanklyn and Cooper, whose work commenced 

 in the laboratory, and whose operations were at 

 first carried out in glass vessels, as is usual in the 

 laboratory, have devised and patented a new still 

 for manufacturing purposes, and with that still, for 

 the first time, vacuum - distillation, or partial 

 vacuum-distillation, becomes generally practicable 

 and efficient. No still hitherto described permits 

 of a sufficiently rapid escape and disposal of the 

 vapour generated in the boiler. The Wanklyn and 

 Cooper still provides for the escape of vapour as 



rapidly as it is- formed in the boiler, which is so 

 perforated that it loses the character of the steam 

 boiler altogether, and no pressure can be got up in 

 it, no matter how the fire may be urged. The 

 perforation is sufficient to allow the vapour to pass 

 out as rapidly as it is formed, and the sufficiency 

 of the condensing and exhausting apparatus, co- 

 operating with the pressureless boiler, enables 

 distillation at reduced pressures to become prac- 

 ticable and economical, and of great utility in 

 various processes of manufacturing industry. 



ANIMAL HAIRS. 

 By John R. Lord. 



T N an early chapter in the history of the develop- 

 ment of the multicellular animal from the 

 ovum, the germinal area is composed of three 

 layers : an outer one (the epiblast), an inner one 

 (the hypoblast), and an intermediate one 

 (the mesoblast). 



From the epiblast there are ultimately 

 developed the central nervous system, 

 the epidermis, the hair, the nails, the 

 enamel of teeth ; in birds the feathers ; in 

 fishes and other organisms the scales 

 and the sensitive epithelium of the 

 special sense organs. From the hypo- 

 blast the secretory epithelium of the 

 alimentary canal is developed together 

 with all the glands opening into it. The 

 rest of the systems are developed from the 

 mesoblast. 



In a previous number of Science-Gossip (O. S. 

 1S93, page 54) I placed before the reader some 

 facts in connection with the structure and uses of 

 feathers. I will now deal with another derivative 

 of the epiblast, which is the hair. Before con- 

 sidering the varieties and 

 uses of hair it will be better 

 to study its structure. 



The structure of the hair 

 with its appendages is very 

 similar to that of the skin. 

 There are facts which point 

 out hair as being only a 

 modification of the skin. 

 Such being the case, it 

 will be necessary to touch 

 briefly on the structure of 

 the latter. 



The skin is divided into 

 two parts : the dermis 



or cutis vera and the epidermis. The epidermis 

 consists of stratified epithelium placed not on a 

 specialized basement membrane, but on a hyaline 

 layer in which is imbedded a reticulum of fine 



Fig. 2. — A diagra- 

 matic section of a hair 

 in its follicle— [J.R.L.] 



Fig. 1. — The cuticle and cortex of a hair 

 Landois.] 



elastic fibres. The dermis consists of connective 

 tissue arranged in bundles, which cross and re-cross, 

 forming a network, the meshes of which are coarser 

 the deeper they are placed The epidermis is 

 composed of several layers of cells, and 

 with the microscope it can be seen that 

 these layers present different character- 

 istics. The lowest layer is known as 

 the stratum Malpighii. It consists of 

 several rows of irregular cuboid cells, 

 the cells being peculiar in the fact that 

 they are joined together by bridges of 

 protoplasm, leaving channels for the 

 circulation of lymph. The lowest cells 

 of this layer are in a rapid state of 

 division, and in a favourable section 

 several karyokinetic figures may be seen. The 

 cells of this layer proliferate rapidly, forcing the 

 older cells upwards to form successively the 

 strata above. 



The next layer is the stratum granulosum, a very 

 thin layer composed of granular cells, the granules 

 being composed of an intermediate substance in 

 the formation of keratin. 

 The st rat it m lucidum, another 

 thin layer, is placed imme- 

 diately above, and is com- 

 posed of homogeneous and 

 transparent elongated cells. 

 These two layers are pro- 

 bably used in the formation 

 of the nails. Superficially 

 the stratum corneum is placed. 

 It is a horny layer, the 

 deeper cells of which retain 

 their nuclei ; but the more 

 superficially the cells are 

 placed the more flattened 

 become, till on the surface 

 of keratin. On examining 

 the surface of the skin certain ridges or furrows 

 can be seen. Into the furrows open the ducts of 



-I After 



and 



horny they 

 found scales 



