244 SUMMARY OF CURRENT RESEARCHES RELATING TO 



perfectly able to do so, but are entirely comparable, from the morpho- 

 logical point of view, to animals devoid of chlorophyll. This life of 

 algse in common with animals is one of the strangest things which 

 can be conceived. Morphologically it is the algae which are the 

 parasites, but physiologically the animals." 



"Yellow Cells" of Radiolarians and Coelenterates.* — Mr. P. 

 Geddes was also simultaneously (and independently) working at the 

 same subject as that which had engaged Herr Brandt's attention 

 (forming the subject of the preceding note), and in a communication 

 to the Royal Society of Edinburgh he deals with the vexed question 

 as to the nature of the " yellow cells " also, presenting an interesting 

 aspect of the economic inter-relations of the animal and vegetable 

 kingdoms. 



The author's researches on animal chlorophyll had already shown 

 that such animals as Convoluta, Hydra, and Spongilkt vegetated by 

 their own intrinsic chlorophyll ; and he now shows that certain Radio- 

 larians and Coelenterates vegetate, as he terms it, " by proxy, by 

 rearing copious crops of Algae in their own tissues, and profiting by 

 their vital activities." Cienkowski and others have already contended 

 that the " yellow cells " in question were algse, for the reason, among 

 others, that they continued to live and multiply long after the death 

 of the animal, but the subject was obscured by contradictions. After 

 repeating the observations of Cienkowski on the Radiolarian yellow 

 cells, the author undertook an independent examination, which 

 established their character as true algae. Not only is their mode of 

 division thoroughly algoid, but starch, as described by Haeckel, is 

 invariably present. The cell-wall is of true vegetable cellulose, and 

 the yellow colouring matter is the same as that of diatoms. In Velella, 

 in sea anemones, and in a Rhizostome Medusa (Cassiopeia horhonica), 

 similar organisms were found. 



Alluding to the methods of examination, Mr. Geddes says that the 

 failures of former observers in obtaining these reactions have been 

 simply due to neglect of the ordinary botanical precautions. Such 

 reactions will not succeed until the animal tissue has been preserved 

 in alcohol and macerated for some hours in a weak solution of caustic 

 potash. Then, after neutralizing the alkali by means of dilute acetic 

 acid, and adding a weak solution of iodine, followed by strong sul- 

 phuric acid, the presence of starch and cellulose can be successively 

 demonstrated in the same preparation. " Thus, then, the chemical 

 composition, as well as the structure and mode of division, of these 

 yellow cells are those of unicellular algfe. I therefore propose for 

 this alga the generic name of Philozoon, and distinguish four species 

 differing slightly in size, tint, mode of division, &c., to which the 

 names of P. radiolariarum, P. siphonophorum, P. adiniarum, and P. 

 medusarum, according to their habitat, may be conveniently applied." 



The mode of life and functions of the organisms are fully dealt 

 with. Reminding us that the colourless cells of a plant share the 

 starch formed by the green cells, Mr. Geddes urges that it is impos- 



* Nature, xxv. (1882) pp. 303-5. 



