POND LIFE. 245 



Chloride of Palladium. — To dissolve in water, a slight quan- 

 tity of muriatic acid must be added, strength about o. i per cent. 

 Half an ounce or an ounce of this fluid hardens, ready for cutting, 

 a piece of tissue the size of a bean, and also colours it in two or 

 three days. It is especially adapted to striated and smooth mus- 

 cles, which become brownish and straw-coloured ; epidermoid and 

 gland-cells become yellow; medulla of nerves become black by 

 direct action ; it renders nuclear formations more apparent. 

 Unfortunately, with many tissues, as brain and epidermis, its 

 action is quite superficial. Wash carefully and mount in gly- 

 cerine. 



ponif Xife. 



Lectures delivered to the Albany Naturalists' Club, Edinburgh, 



By William Evans Hoyle, M.A. (Oxon), 

 F.R.S.E., M.R.C.S., 



Naturalist to the " Challenger " Expedition Commission 



Second Lecture. 



IN the last lecture we were chiefly concerned with the lower 

 plants ; I shall ask your attention to-night to the vegetable 

 kingdom, and then go on to the animal. There are a very large 

 number of plants in our ponds, but I do not think it would be 

 worth while to enumerate their names. You will remember in the 

 last paper that I told you how the Algae reproduce themselves, 

 and I showed you that in almost every case the reproduction 

 was effected by means of two cells uniting with each other. One 

 of these is generally larger than the other, and is fixed ; it is 

 generally spoken of as the female cell, while the smaller and more 

 active cell, which moves or is moved towards it, is called the 

 male cell. 



The former are found in the ovules of flowering plants and 



