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



— by M. de Quatrefages. For the details I must refer to that ob- 

 server's paper in the ' Annales des Sciences,' but I may state that its 

 structure is essentially similar to that of Thalassicolla nucleata, sup- 

 posing that the latter had given exit to its central cell by a depression 

 at one point of its surface. Noctiluca, however, appears to feed after 

 the manner of Actinophrys, and perhaps conjugates also, as M. de 

 Quatrefages " has met with double individuals two or three times." 

 This he considers an evidence of spontaneous fission ; but further 

 observation might have reversed this judgement, as it did that of 

 Kolliker with regard to Actinophiys. 



From the invariable adhesion of grains of sand to one part of the 

 surface of Noctiluca, it would seem to be set free from some unknown 

 fixed form which is probably analogous in its structure to Thalassicolla 

 punctata. 



To sum up the different lines of argument it may be said — ■ 



1. That the Thalassicolla punctata is not an exceptional form of 

 animal life, but belongs to the same great division as the Sponges, 

 Foraminifera, Infusoria, and Gregarinidae, — the Protozoa or unicellular 

 animals. 



2. That the Protozoa have definite characters as a class, which 

 are — 



a. That they are either simple nucleated cells or aggregations of 



such cells, which are not subordinated to a common life. 



b. That they have a mode of reproduction consisting in an endo- 



genous development of cells, preceded by a process analogous 

 to the conjugation of the lower plants. 



3. That the Thalassicolla nucleata closely resembles Actinophrys 

 Sol, which is known to conjugate, and which there is great reason to 

 believe is the reproductive stage of one of the Vorticellinae. 



4. That as Th. punctata is one of the Protozoa, it most probably 

 has a reproductive stage. 



5. That Th. nucleata might readily be derived from such an altera- 

 tion in one of the cells of Th. punctata as occurs in the sponge-cells 

 when they go to form the seed-like body, or in the Gregarina-cells 

 when they become " Navicella-sacs." 



6. That Thalassicolla nucleata is essentially similar in structure to 

 Noctiluca. 



Finally, I may be permitted to say, that no one can be more fully 

 conscious than myself of the slender and hypothetical grounds on 

 which some of these conclusions rest. My chief purpose has been 



