i62 NATURAL SCIENCE. Sept.. 



organ is a secretory organ, and that its action is to raise the blood- 

 pressure. 



The Minute Structure of Spleen. 

 In the Joiii'iial of Anatomy and Physiology for July, 1895, Dr. E. W. 

 Carlier describes a new method for investigating the structure of the 

 spleen. Everyone knows that it is most difficult to obtain preparations 

 of the spleen in which the minute structure is properly shown. In an 

 animal that has died naturally, degenerative changes have begun 

 in the spleen before preparations can be made ; even in a freshly- 

 killed animal the ordinary methods of " fixing" the protoplasm leaves 

 much to be desired. Dr. Carlier proceeded by anaesthetising the 

 animal deeply. The thorax was then rapidly opened, the apex of the 

 heart removed, and a cannula fastened in the aorta. All the blood in 

 the animal was then washed out by irrigation with normal saline 

 solution, heated to the temperature of the animal's body. Imme- 

 diately afterwards the saline solution was replaced by a warm solution 

 of picro-corrosive sublimate. This penetrated into the smallest 

 capillary of the animal's body and killed and fixed every cell in every 

 organ in its normal condition. 



The Ccelome and Nephridia. 



Not long ago it was held that animals like Hydra possessed one 

 cavity, the ccelenteron, communicating with the exterior by the 

 mouth ; while the Ca-louiata, from the lowest worms up to man, were 

 built on the plan of one hollow cylinder within another. The 

 inner cylinder, opening at one end by the mouth, at the other 

 by the anus, was t^e alimentary canal : the space between the 

 alimentary canal and the body-wall was the coelome. Subsequent 

 research has modified the primitive simplicity of this view. 

 The " coelome " and " coelomic spaces " are certainly not spaces 

 of the same order in different sets of animals. Among the 

 spaces we have first learned to separate " haematocoeles," or blood- 

 spaces, which are the most conspicuous cavities between the 

 alimentary canal and the outer body-wall in many animals. But, 

 more recently, distinctions are being made among coelomic cavities 

 that are not " haematocoeles." In a valuable paper in the Quarterly 

 journal of Microscopical Science (June, 1895) Mr. Edwin S. Goodrich, 

 one of Professor Ray Lankester's assistants at Oxford, puts together 

 in a luminous fashion the results of later investigations. According 

 to his excellent account, the ccelome is essentially a genital pouch„ 

 or set of pouches, hollowed out in the mesoblastic somites, and 

 giving rise to the genital products. In simple cases, like AmphioxuSy 

 the most anterior of these pouches arise as direct outgrowths from 

 the archenteron ; but, however they arise, they most frequently fuse 

 below the gut into a wide chamber lined by peritoneum and popularly 

 known as the coelome. From this chamber ducts grow outwards 



