22 Transactions. 



mens and numerous microscoincal drawings. He said: — The group 

 of plants which is known by the name of i^'i^icesor Ferns forms one 

 of the most interesting and beautiful in the vegetable world. The 

 natural order of Filices is the most important section of the sub- 

 kingdom of cryptogamia, or flowerless plants, and is distributed 

 over the surface of the globe except the colder regions of the 

 frigid zones. It includes about 3000 different species, which vary 

 in size from about half-an-inch to more than 50 feet ; and only 

 47 of these are indigenous to the British Isles. For more than 

 500 years these plants have excited the admiration of all classes 

 of society, and were regarded by the superstitious to be more or 

 le.is connected with the supernatural. During the greater portion 

 of this time their method of propagation was a mystery, but it was 

 thought that the " black spots" which were found on the backs of 

 the fronds had something to do with it. Owing to the improve- 

 ments made on the compound microscope, this vexed question of 

 botanists was at length solved by the unceasing exertions of 

 Nageli and Count Suminski. The first account of the develop- 

 ment was published by Nageli in 1844, and, although erroneous in 

 some particular.?, it was in the right direction, but the credit is 

 due to Count Suminski, who some years later discovered the 

 true method. I shall not occupy your time in describing these 

 discoveries, or the difference between them, but proceed to the 

 subject of this paper. 



If we look at the under surface of a ripe frond we find that it 

 is moi-e or less covered with minute reddish-brown patches resem- 

 bling scales, which, if we examine closely, prove to be arranged in 

 small groups, or in some ferns, in short lines along the margins, 

 called sorii. I have here several fronds of different ferns on 

 which the arrangement of the sorii may be observed with the aid 

 of this small magnifying glass. In the polypodies {Polypoduim), 

 the buckler [Lastrea), and the shield ferns {Polystichum) the soiii 

 are circular, in the spleenworts (^Asplenium), the hart's tongue 

 {Scolojyendruom), and the hard fern [Blechnam) they are linear ; 

 while in the bracken (Pteris) and maiden-hair {Adiantiom) they 

 occur at the margin of the frond. On examining a sorus of either 

 the polypody or lastrea, with 1-inch objective, we find that it is 

 composed of a number of minute rounded capsules or pouches, 

 supported on short stalks and arranged in a circular cluster, and 

 these are called siwrangia, thecce, or spore-cases. In \jhefilix lastrea 



