PROGRESS OF MICROSCOPICAL SCIENCE. 263 



by a writer in the ' American Naturalist ' (Marcli) . The original 

 memoir contains thirty beautiful illustrations. Tlie wax does not 

 appear to be a simple coating over the surface, as though it might 

 have been laid on liquid with a brush, forming a continuous layer. It 

 is seen to be rather a dense forest of minute hairs of wax ; each one 

 sitting with one end upon the epidermis and the other either rising up 

 straight or rolled and curled among its neighboiu's. This matting 

 of waxen hairs often becomes so dense that when examined from the 

 surface it presents to the microscope the appearance of a continuous 

 layer, while a carefully-made section of the leaf, or skin of the 

 fruit, shows its true structure. The question from what part of the 

 epidermis or sub-epidermal tissue does the wax come, is most 

 beautifully and clearly answered. Professor De Bary says that in the 

 cell-contents there cannot be discovered the slightest trace of wax, 

 and the statement that the chlorophyll is partly made of wax is 

 totally erroneous. The locality in which it can be first detected is 

 the cuticle and the cuticularized elements of the epidermis cells. 



The Odontoblasts of Teeth. — Mr. T. C. White, the secretary to 

 the Quekett Club, lately read before that Society a very interesting 

 paper on the above subject. Mr. White agrees most generally with 

 the views already laid down, and he showed the Society his method of 

 examining the teeth, which is certainly of importance. His remarks 

 on the subject of the odontoblasts are of interest. He says that about 

 the seventh month of foetal life the ossification of the tooth com- 

 mences, and the dentine is represented by a cup-shaped scale capping 

 the crown, and ultimately extending down the sides and embracing 

 the whole of the upper surface of the pulp. It is at this period of 

 their growth that the odontoblasts are most active, for they have the 

 development of the dentine before them, and deriving a plentiful 

 siipply of nutrition from the plexus of blood-vessels beneath them, 

 dentine is formed through their agency from without inwards, till the 

 pulp being reduced to the size at which we generally see it by the 

 gradual formation of the dentine, the odontoblasts become dormant, 

 but capable of awaking to activity under the influence of certain 

 circumstances of irritation ; thus if caries attacks a tooth at a 

 particular spot the tubuli in the dentine, through the fibrillfe in them 

 become consolidated at an equal distance from the point of attack all 

 round it, and a barrier seems to be thus thrown uj) against the inroads 

 of the advancing enemy ; but unless such a remedial measure as the 

 careful excavation of the carious j)ortion of the tooth and subsequent 

 plugging of the cavity be adopted, barrier after barrier may be thrown 

 up but to be overcome. Even then the odontoblasts of the pulp resist 

 by forming new dentine in its very substance, and it is only when 

 inflammation and suppuration destroy the odontoblasts that this 

 reparative process is annihilated. Mr. White's mode of preparing the 

 tooth should also be read. — Vide QueJcett Club Journal, April. 



The Penis of the Flea. — Mr. W. H. Furlonge has a paper in the 

 last number of the ' Journal of the Quekett Club,' in which he enters 

 very fully on the anatomy of the flea. Most of his researches have 



