JOURNAL OF MICROSCOPICAL SCIENCE. 



DESCRIPTION OF PLATE XII, 



Illustrating Mr. Brightweirs paper on Noctiluca. 



Fig. 



1. — Front view, showing the tail, cilium, &c. 



a. A vacuole containing a bright red-brown granular mass. 

 2. — Side view, showing pyriform shape, position of the fissure, &c. ; struc- 

 ture obscure, from the quantity of food contained in the animal, 



a recently captured specimen. 

 3. — ^View showing the somewhat thickened angular portion ; the nucleus 



is generally situated opposite to this, as well as the origin of the 



tail, so as to be indistinct in this view. 

 4. — Specimen in which the tail was undeveloped ; most of the individuals 



taken dming the winter months were thus imperfectly formed. 

 5. — Early stage of self-division : division of the nucleus has just taken 



place. The perfect development of the new tail at this period is 



remarkable. 



6. — Division somewhat further advanced ; the nuclei have removed far 

 apart and a fissure is commencing. The vacuoles in this indivi- 

 dual (which was drawn with great care) have almost entirely dis- 

 appeared. 



7. — Shows a further progress towards division. 



8. — Shows self-division nearly complete, and two individuals now only held 

 together by a slender cord. 



9. — An individual just after complete separation and before the connecting 

 portion is absorbed. 



10. — Abnormal portion of the body thrown off by the animal, and in which 

 no nucleus is found. 



11. — Shows the effects of gentle, steadily continued pressure. At the first 

 an appearance, as of a most delicate sac, is pi'otruded, into which the 

 globules, vacuoles, and sometimes the nucleus are received. The 

 inner menbranes peel off from the cell-wall, and when the contents 

 are out the creature suddenly collapses entirely. The appearance of 

 the sarcode (membrane and threads) gently leaving its connections, 

 "like threads of a very viscid liquid," and collapsing, is very remark- 

 able. 



12.— Oral orifice, &c., x 200. 



13. — " Prehensile organ " and " trembling organ," x 400. 



14, — Cell-wall, x 400 ; a tolerably thick, firm, and resisting structureless 

 membrane. 



15. — Sarcode membrane, with its thickenings, forming the immediate inter- 

 nal investment of the cell-wall. The thicker portions form a toler- 

 ably regular network over it; from these spring the fibrils. 



16. — Tail, showing a section, x 400. This is concave in the part wliich 

 comes in apposition to the body, and convex in the part which 

 reaches beyond the body. 



