84 NOTES AND OBSERVATIONS ON BOARD H.M.S. RATTLESNAKE 



I. The central portion. — This consists of a granular mass inter- 

 penetrated in every direction by short, cyHndrical, transparent rods, 

 which form a sort of networl-:. At the margins of the central portion, 

 however, the rods become gathered into bundles, and they are 

 longer and lie parallel to one another. In this form they enter the 

 intermediate substance and form the radii before mentioned. When 

 they reach the cortical substance, the majority of the rods diverge and 

 become spread out ; a few however remain as a bundle, and reach the 

 edge, or even project a little beyond it. 



Besides the bundles, a great number of long, solitary rods traverse 

 the intermediate substance radially. 



The rods are cylindrical, and about o-tV TT^h of an inch in diameter. 

 They are all perforated by a very narrow central canal, so as to- 

 appear like minute thermometer-tubes. 



2. The cortical substance consists of two zones, an inner and an 

 outer, which pass insensibly into one another at the line of contact. 



The inner is composed of a mass of thick bundles of a fibrous 

 tissue, so interwoven that a slice presents every possible section of 

 them. The rods penetrate this zone, and a very few of the stellate 

 bodies are found scattered through it. 



The outer zone is dense, granular, and otherwise apparently struc- 

 tureless. Scattered through it are great numbers of crystalline spheres 

 beset with short conical spikes. 



3. The intermediate substance. — This consists of a granular 

 substance in which ova and stellate crystalline bodies are imbedded. 



The ova are of various sizes. The largest are oval and about ^--Joth 

 of an inch in long diameter. They have a very distinct vitellary 

 membrane, which contains an opake coarsely granular yelk. A clear 

 circular space about xisVuth of an inch in diameter, marking the 

 position of the germinal vesicle, is seen in the centre of each ovum, 

 and within this a vesicular germinal spot ^-oVu^h of an inch in diameter 

 is sometimes visible, although with some difficulty, in consequence of 

 the opacity of the yelk. 



The stellate bodies are about iTrVirth of an inch in diameter : they 

 appear to be of a similar nature to those described in the cortical 

 substance, but they are smaller ; and while the radii are proportionally 

 long, there is hardly any centre beyond that formed by their meeting. 

 The granular uniting substance is composed entirely of small 

 circular cells about ^^yth of an inch in diameter, and of spermatozoa 

 in every stage of development from those cells. The cell throws out 

 a long filament which becomes the tail of the spermatozoon, and 

 becoming longer and pointed forms, itself, the head. 



