441 



The common envelope of the entire and perfect Malpighian 

 body differs structurally from the true capsule ; the latter is 

 thin and structureless, the former, thick, and constituted of a 

 delicately fibrous and nucleated form of elastic tissue. 



Mr. Toynbee * is the only writer, with whose observations 

 I am acquainted, who understands the true character of what 

 is ordinarily regarded as the " capsule of the Corpus Malpi- 

 ghianum : " this he correctly describes as being a distinct glo- 

 bular investment, and not, as was supposed, an expansion of 

 the tube. 



Notwithstanding, however, the knowledge of this fact, Mr. 

 Toynbee's views of the structure of the Malpighian body 

 appear to me to be far from correct. 



Thus Mr. Toynbee describes the Malpighian body as " com- 

 posed of two distinct elements a plexus of blood-vessels, 

 and a membranous capsule, which completely surrounds and 

 envelopes the plexus." 



Each Malpighian body is indeed composed of two distinct 

 and essential elements, the dilated extremity of the uriniferous 

 tube embraced and surrounded by the Malpighian plexus : 

 the outer investment, called by Mr. Toynbee and others " the 

 capsule," is not a structure essential to the Malpighian body, 

 since it alike invests this and the uriniferous tube for its 

 whole length attached to it. 



Again, Mr. Toynbee describes the uriniferous tube, after 

 penetrating the capsule, as twisting into a coil, and, after being 

 in contact with the ramifications of the corpus, as emerging 

 from the capsule. 



This last statement shows that Mr. Toynbee was unac- 

 quainted with the proper character of the most important and 

 essential of the two elements of the Corpus Malpighianum, 

 viz. the dilated extremity of the uriniferous tube, filled with 

 its secreting cells. 



* On the Intimate Structure of the Human Kidney, and on the changes 

 which its several parts undergo in Bright's Disease. By Joseph Toynbee, 

 F.R.S. June, 1846. Medico Chirurgical Transactions. 



