426 Dr. G. Meissner on the Genus Merinis. 



of termination of the nerve-fibre, the fibrillar structure is never 



/v Digestive Apparatus. — This structure, according to Meissner, 

 presents so many peculiarities and is so widely different from any- 

 thing observed in other animals, that we almost relinquish any 

 attempt to give even a brief description of it, without the aid of 

 figures. In the first place, the alimentary canal has no anal or 

 excretory passages, and therefore the food and assimilation must 

 be such as to leave little or no so-called faecal matter. 



From the circular buccal orifice a semi-canal proceeds a short 

 distance, when it passes into another structure. This semi-canal 

 is the oesophagus. The structure into which it passes is a tube 

 quite small at first, but which soon expands ; it is filled with a 

 finely granular sponge-like substance, and is alternately dilated 

 on each side into sacs. Through this laterally varicose tube 

 the semi-canal of an oesophagus extends to its very end. Sup- 

 pose then a tube with alternate lateral dilatations, filled with a 

 spongy substance, and through which runs a semi-canal or half- 

 tube like an oesophageal groove. Each of these dilatations has an 

 inversion — a folding in of its internal membrane, producing an 

 infundibuliform body in the dilatation itself. This body opens 

 through a prolongation of the external membrane of the dilata- 

 tion, w^hich is continuous into a tube connecting with some adipose 

 receptacles. 



The food passes along the semi-canal or groove, is gradually 

 absorbed by the spongy substance filling the dilatation, thence 

 passes into the invested body by endosmotic absorption, and is 

 then conveyed as assimilated material into the fat-receptacles 

 which lie in the cavity of the body. These receptacles are store- 

 houses of nutriment and are particularly enlarged and developed 

 during the larval condition, — their contents being used for the 

 formation of the sexual parts afterwards. Now as there is no 

 vascular system in these animals, the dispersion of the nutrient 

 material for the growth and substance of the various tissues must 

 take place by permeation and endosmosis from the fat-bodies 

 which extend over and between all the organs. This assimilation 

 without any particular excretion is a remarkable fact ; but it 

 appears more conceivable when we bear in mind the oeconomy 

 of the animal. Its larval or parasitic state is like that of insects 

 — merely preparatory for the ulterior changes of its full develop- 

 ment. During this time its food is probably mostly pure fat, 

 which has only to be taken up and stowed away as material for 

 the development of the reproductive organs. This last ensues 

 during a quiescent state, and after the full discharge of the 

 sexual functions, the animal probably dies. 



Genitalia. — Males. — The disparity in numbers of males and 



