M 



On the Histological Development of the Larva of 



corethra plumicornis. 



ByT. Charters White, M.R.C.S., L.D.S., &c, &c. (President). 



(Read Feb. 24, 1882 J 



Plate II. 



For investigating any of the mysteries of biological science the 

 student is generally recommended to avail himself of those simple 

 demonstrations of life which nature so abundantly supplies to all who 

 seek for them. Examples present themselves on every hand, but in 

 no case so ready to our use as in aquatic life, whether animal or 

 vegetable, and by carefully studying them we are enabled to watch 

 and record operations in many respects similar to those taking 

 place in that mysterious laboratory which every man carries about 

 with him in his own body, and which in their totality make up the 

 sum of his daily life. This recommendation was brought home to 

 my mind with much force while examining the changes taking 

 place in a larva of Corethra plumicornis, which, being kept under 

 observation on the stage of my microscope, enabled me to watch 

 the gradual development of its various tissues and organs. The 

 interest felt in this observation would have been intensified had I 

 been able to have watched its development from the egg, but in the 

 present case its internal organs were in a tolerably advanced state 

 of growth, sufficient of its development, however, being wanting to 

 furnish much interesting work for observation and to supply me 

 with notes for a short communication this evening, leaving the 

 earlier stages of this creature's development to be worked out by 

 those fortunate enough to procure its eggs, when it would be 

 interesting to bring its life-history up to that stage in which it 

 usually appears before us, and in which it was presented to me. 



The external form of this creature is so well known to all micro- 

 scopists that I need not occupy your time and attention by any 

 lengthened description of it, but it may aid our subsequent exami- 

 nation if we note that its body is divided into eleven segments, the 

 head being the first, the thorax the second, followed by nine abdo- 



