PHYSIOLOGY OF THE INVERTEBRATA. 8i 



of VdcUa and Forjnia, as described by Voigt. Subsequently 

 Haeckel found starch in tliese cells, and concluded that this 

 fact supported the idea of the nutritional function previously 

 assigned to them by himself.* 



" Cienkowskif in 1871 endeavoured to show that the yellow 

 cells of Radiolarians were parasitic algte, since they survived 

 the death of their host, and multiplied subsequently, passing 

 through an amceboid and encysted state." 



There is no doubt that the " yellow cells " do survive for 

 some time in the bodies of dead Radiolarians; but in regard 

 to Hydra and Spomjilla^ Prof. E. Ray Lankester:}: has shown 

 that " the chlorophyll corpuscles of these animals are not algee 

 at all (as stated by Dr. Brandt §), but differ in no essential 

 respect from the chlorophyll bodies of plants." 



Dr. 0. A. MacMunn|l has shown that "the chlorophyll 

 bodies of Spongilla., Hydra, Faramcecium, Ophrydmm, Vortex; 

 viridis, and Stcntor polymorphns are of different size, colour, 

 and give different reactions, and a different spectrum, from 

 the ' yellow cells ' of Adinicc. With regard to size, the 

 ^ yellow cells ' of Anthca cci-eus were found to measure I2ju 

 (= 12 X y^^ojy mm.), or I3ju down to iOfi\ while in Para- 

 mcecium they measured from 6fx down to 3ju — i.e., less than 

 half the size of the former ; in Hydra viridis mostly from 

 6/1 to 4/i. The colour is a dull brownish-yellow in the 

 ' yellow cells ' of Antliea, &c. ; while it is a fine green in the 

 Infusoria and Hydra. The spectrum in Spongilla, in Hydra, 

 and in the Infusoria is that of plant chlorophyll ; while in 

 the ' yellow cells ' it is that of chlorofucin." 



The chief function of animal chlorophyll and allied pig- 

 ments is that of respiration ; but it is probable that these 

 pigments play an important part in sexual selection, in 



* Jena Zeitsch. 1870, p. 532. 4 

 t Archiv. Mikro. Anal. 1871. 



J Quarterly Journal of Microscopical Science, vol. 22, p. 229. 

 § Jlonatsb. Akad. Wiss. Berlin, 1881. 



jl Proceedings of Birmingham Pliilosophical Society, vol. 5, pt. i, p. 212. 



F 



