322 SUMMARY OF CURRENT RESEARCHES RELATING TO 



a rock, certain structures exhibiting apparently organic cells, are they 

 the remains of true organisms or of pseudo-organisms ? This con- 

 sideration, at least till it has been further studied, is not without its 

 bearing upon such questions as the organic or mineral nature of the 

 structures found in meteorites, and, e. g., of Eozoon canadense. 



B. INVERTEBRATA. 



"Symbiosis of Animals with Plants "—Chlorophyll-corpuscles 

 and Amyloid Deposits of Spongilla and Hydra.* — Professor E. E. 

 Lankester discusses this sulvject in an interesting article, with special 

 reference to the recent views of K. Brandt f (endorsing those of 

 Semper) that the green-coloured corpuscles found in the cells of 

 Spongilla Jluviatilis and Hydra viridis are not similar in nature to 

 the chlorophyll-bodies of plants, but are parasitic or " symbiotic " 

 unicellular algfe. 



Whilst Professor Lankester considers that there is " very nearly 

 sufficient ground" for accepting the existence of " symbiosis" so far 

 as regards the " yellow cells " of Anthozoa and Eadiolarians, yet he 

 regards Semper and Brandt's extension of it to Spongilla and Hydra 

 as not justified. It appears to him that the green-coloured corpuscles 

 found in the latter case are clearly similar in nature to the chloro- 

 l^hyll-bodies of green plants, and that " there is no more reason to 

 regard them as symbiotic algee than there is to regard the green 

 corpuscles in the leaf of a buttercup as such." 



In the course of the discussion it is pointed out that the investi- 

 gation of the claims of any given greenish-coloured pigment to be 

 regarded as " chlorophyll " is by no means a simple matter. Suj)- 

 posing the pigment to be soluble in alcohol, we still have to ascertain 

 which of Sorby's three groups (chlorophylls, xauthophylls, lichno- 

 xanthines), are present, and which of each of the species distinguished 

 by him within those groups. 



In order to do this we have to rely on : — 



1st. Variations in degree of solubility in such media as alcohol, 

 ether, benzine, carbon bisulphide. 



2nd. Absorption spectra of the series of solutions obtained. 



3rd, Fluorescence and spectrum of the fluorescent light of such 

 solutions. 



4th. Reactions of the solutions with acids, alkalies, and oxidizing 

 and reducing agents, which give rise to new compounds or change 

 the spectra characteristically. 



There are, however, two other categories of phenomena in relation 

 to the chlorophyll-bodies of green plants which comprise data of a 

 nature to assist us in judging of the similarity or dissimilarity of the 

 green pigments of animals compared with that of the chlorophyll- 

 bodies. There are, Sthly, the physiological activities associated with 

 the chlorophyll-bodies of j)lants ; and 6thly, the morphological features 

 of these bodies. 



* Quart. Jourii. Micr. Sci., xxii. (1882) pp. 229-54 (1 pi.), 

 t See this Journal, ante, p. 241. 



