( 1<! ) 

 PEOGEESS OF MICEOSCOPICAL SCIENCE. 



Bistology of the Leaf of the Tea-plant, and Value of Potass in such 

 Investigations. — The parenchyma of the leaf of Thea viridis abounds 

 in sphseraphides ; the margin of the cells of the epidermis are alike 

 sinuous on both sides of the leaf; only apt to appear confused on the 

 upper surface from the adhesion of some of the rounded or oval cells 

 of the subjacent parenchyma; on the under side there are simple 

 unicellular hairs and oval stomata. All these points may be very 

 easily displayed by soaking the fresh leaf in a solution of caustic 

 potass, and often still better by boiling the part in that alkaline fluid. 

 And, as observed by Mr. Gulliver in his paper on the short prismatic 

 crystals in several parts of leguminous plants, and in the testa of 

 other orders, published with a Plate in the last number of this 

 Journal, the potass is very valuable in separating vegetable fibres, 

 membranes, and cells ; and in clearing parts so as to expose many 

 plant-crystals, otherwise but dimly seen, as was shown experimentally 

 by him in the leaves of tea at a late meeting of the East Kent Natural 

 History Society, at Canterbury. 



The Various Doctrines as to the Development of Bone. — Professor 

 Kolliker has published a work of great importance on this subject. 

 It appears in the 'Proceedings of the Physico-Medical Society of 

 Wui-tzburg,' and has been very ably noticed in the ' Medical Pi,ecord,' 

 by Dr. E. Klein. "With regard, first, to the typical resorption of 

 bone-tissue. Dr. Klein says that the doctrine of the normal resorption 

 of bone-tissue by ostoclasts (myeloplaxes), in the Howship's lacunae of 

 resorption, brought forward by Kolliker, has been lately contradicted 

 by Strelzoff, who found that bone-tissue, once formed, never is resorbed 

 again, but grows interstitially. In the present paper Kolliker brings 

 forward some new facts to meet these objections. At the diaphysal 

 extremities of long bones, the external resorption attacks, first, the 

 periostal portion of the bone-cortex. This being here very thin, the 

 intracartilaginous bone therefore is soon involved in the process of 

 resorption. Such resorjition-lacunsB remain for many years in the 

 superficial layers of the intracartilaginous bone. In transverse sections 

 throu-^h the humerus of a human foetus, especially if they are stained 

 with hsematoxylin, this is quite clearly to be seen. Such sections, if 

 they are made through the upper extremity of the diajihysis, show 

 laterally a distinct periostal cortex, and on its external surface an 

 apposition of bone-substance. At the median side, however, this peri- 

 ostal cortex is absent altogether, and the periost is in immediate con- 

 tact with intracartilaginous bone, in which the residua of the trabeculse 

 of the cartilaginous matrix are brought out remarkably well by hsema- 

 toxylin — a fact first pointed out by Strelzoflf himself. At, these points 

 the surface of the intracartilagiuous bone contains very numerous 

 Howship's lacunje, and in them, as usual, osteoclasts. Transverse sec- 

 tions through the tibia below the condyles show exactly the same. 

 Principally, the same was found in the tibia of a male aged fifteen years. 



