PROCEEDINGS OF SOCIETIES. 



EOTAL MiCEOSCOPICAL SoCIETT. 



December Srd, 1873. 

 Chaeles Beooke, Esq., F.R.S., President, in the chair. 



A PAPEE was read by the Rev. W. H. Dallinger and Dr. J. 

 Drysdale on " further Researches into the Life- History of the 

 Monads," in continuation of that read at the November 

 meeting. 



The authors subjected, as before, certain forms of monads 

 obtained in a maceration-fluid to continuous observation with high 

 powers, especially with a view to discover the method of increase 

 or multiplication. Fission has not proved in any case persistently 

 inquired into by them to be the essential method of multiplica- 

 tion ; though, since it is an accurate statement of facts so far as 

 they go, it is not surprising that it should be generally accepted 

 as the entire method. Nor has fission itself, they think, in these 

 minute forms, been described with sufficient care. It is not a 

 mere division of undiff'erentated sarcode into two parts. Before 

 separation takes place there is always a germination of the 

 anatomical elements, which make the new monad complete; 

 while in many instances the fission is completed by a suddenly 

 induced amoeboid condition. The original form has two flagella, 

 one permanently hooked, the other flowing. In fission similar 

 structures are formed for each new individual thus produced. 

 Multiplication by this method may continue without apparent 

 interruption for many days ; but eventually two, four, or even six 

 of the monads may unite together, take a flaccid sac-like form, 

 becoming quickly distended, and dividing internally into seg- 

 ments, which go on subdividing till the sac is filled with beautiful 

 oval bodies which eventually escape, and are found to possess a 

 single flagellum ; these rapidly grow, acquiring in a manner not 

 clearly made out the second (hooked) flagellum ; and when thus 

 mature recommence multiplication by fission. This is the com- 

 paratively simple life-history of tlie form. The paper is 

 published at length, with illustrations, in the journal of the 

 Society. 



Mr. Charles Stewart called the attention of the meeting to a 

 section of the leaf of an india-rubber plant, which showed con- 



