ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 71 



general view that tliey consist not of cellular tissue, but of a struc- 

 tureless protoplasmic mass. He finds that these organs not only con- 

 sist of cells, but that an ectoderm and endoderm and even a rnemhrana 

 propria are also present. The endoderm forms a solid axis, which 

 at the base of the organ unites with the endoderm of the stem. The 

 ectoderm, which covers it, is alone the seat of the amoeboid move- 

 ments, which take place chiefly at the superior extremity, where the 

 endodermic axis is wanting. The cause of the movements is explained 

 by the structure of the ectoderm. Its cells are immersed in a con- 

 tractile protoplasmic mass, to whose contractility the movements are 

 due. 



Though these organs have no cavity they may be considered as 

 degenerated polyps : (1) because their tissues are the same ; (2) 

 because each has a calyx ; and (3) because the polyps can in certain 

 circumstances transform themselves into a nematophore. 



The author's observations were made on one species of Flumularia, 

 two of Antennularia, and two of Aglaophenia. In the case of one 

 of the latter he found that the tissues constantly contained parasitic 

 algse ; the endoderm " yellow cells," and the ectoderm a green alga 

 belonging to the Phycochromaceae. 



Green-cells of Hydra.* — In a contribution to the interesting ques- 

 tion of symbiosis, 0, Hamann points out that while Brandt believes 

 that chlorophyll in animals is always associated with the presence of 

 algaa, Geddes finds that supposed chlorophyll-containing animals may 

 have (1) no chlorophyll, but green pigments — e. g. Bonellia ; (2) 

 forms with intrinsic chlorophyll — e. g. Convoluta, Hydra, Spongilla ; 

 and (3) " those vegetating by proxy " in which algas live. The ques- 

 tion that has to be answered is — How do the green-bodies enter the egg 

 of Hydra, which for a certain time is free from them, and which itself 

 arises from the ectoderm, in which green-cells are never found ? The 

 author put some Hydrce into a test-tube, and filled a quarter with 

 water ; when the animals were fully extended he added two drops of 

 1 per cent, solution of acetic acid ; to this drops of 5 per cent, solu- 

 tion of chromic acid were added, until the water had a distinct yellow 

 colour. . The test-tube was then filled up with 70 per cent, alcohol ; 

 the solution drawn off, and alcohol gradually added until it was finally 

 absolute. The animals were coloured by borax-carmine, then brought 

 for a few minutes into absolute alcohol, cleared up with chloroform, and 

 imbedded in paraf&n. In sections the protoplasm of the cells is found 

 to have a rosy colour, while the green-cells retain their original tint. 

 If we direct our attention to the ovary, we see that, so soon as it 

 begins to be formed, there commences an increase of the green-bodies 

 at the corresponding point in the endoderm; and this is evident even 

 to the naked eye, and from the exterior by the darker coloration of 

 the animal at this point. At the time when, to use the words of 

 Kleinenberg, the ovum has the form of a " butterfly with outspread 

 wings," the green-cells are to be observed in it ; they wander into the 

 egg, from the endoderm, at the breaking-down of the supporting 



* Zeitsclir. f. Wisa. Zool., xxxvii. (1882) pp. 457-64 (1 pi.). 



