40 



and stoniata of vegetable tissue. The stomata ai-e mostly in the epidermis 

 on the under side of the leaves. The epidermis is a thin transparent skin, 

 which can be readily separated ; it is composed of a single layer of cells 

 containing air. These are closely fitted to each other, and thus confine the 

 moisture, which otherwise would quickly evaporate by the hot sun, and 

 the leaf soon becomes dried up and withered. The following figures give 

 some idea of their number : — In the house leek 10,700 stomata to the 

 square inch, mistletoe 11,000, and in the vine 13,000. To prepare these 

 structures the leaf is taken and placed in slightly acidiferous water to 

 macerate for a few days, to separate more readily and completely the 

 epidermis from the rest of the leaf ; after being cleansed by gently 

 drawing over a soft sable brush it is ready to stain. The reason for this 

 course is to bring out more clearly details of structure, and may be done 

 by two processes, viz., rapid and slow. In the slow process the tissue is 

 allowed to remain in the staining media a considerable time according to 

 its density ; in the rapid process a stronger fluid is used, and the tissue 

 allowed to remain in only a few minutes. Afterwards the stain is wasted 

 away, and the stain which has permeated through the structure is fixed. 

 It is then ready for mounting on a glass slip with balsam. The three 

 stages of how to prepare, stain, and mount this object for the microscope 

 were clearly shown, and the formula required to obtain these results were 

 also given. Several specimens of epidermis, showing stomata, were 

 mounted and exhibited under the microscope ; slides were also shown of 

 the stomata in the mistletoe, laurel, india-rubber plant, onion, and in the 

 petals of pelargonium and hyacinth. 



Meeting held in Municipal Buildings, February 24th, 1890. John 

 Stubbins, F.G.S., F.E.M.S. (Vice-President), in the chair. 



TRILOBITES. 

 W. LOWER CARTER, M.A., F.G.S. 



Trilobites are extinct marine crustaceans entirely confined to the 

 primary geological beds. Their remains consist of a test generally 

 composed of carbonate or phosphate of lime and certain indications of 

 limbs. They take their name from the body being marked out longitudi- 

 nally into three lobes by two grooves which sometimes extend its whole 

 length. The test is divided transversely into three portions — (1) the 

 head, which is unsegmented ; (2) a segmented body ; (3) an unsegmented 

 tail. The head is generally semi-circular, surrounded by an external 

 raised margin, which may be entire or produced into lateral and posterior 

 spines. The median portion of the head, called the glabella, is usually 

 convex, and is often marked out into lobes by pairs of transverse furrows. 

 The lateral portion of the head are called the cheeks. These are divided 

 by the facial suture into the outer or free cheeks, and the inner or fixed 

 . cheeks, which are attached to the glabella. The eyes, which are compound 



