Nucleus and Trophoplast . 145 



In the multi-nucleat cells of Valonia Schmitz^^ has fre- 

 quently observed division, and always observed it. to take 

 place by constriction. It does not seem to be established 

 with certainty, for all cases, how the nuclei of the swarm- 

 spores originate here and in the case of the other Siphono- 

 cladiaceae, whether through direct or indirect division. 



In this connection it should be mentioned that, accord- 

 ing to Van Beneden and Julin, direct and karyokinetic 

 nuclear divisions alternate in the spermatogenesis of As- 

 caris megalocephala.^^ Thus we see that this subject is 

 not yet ripe for theoretical use. 



The amyloplasls, with all their derivatives, among 

 which the chlorophyll bodies are the most important, Ar- 

 thur Meyer calls trophoplasts. In the lowest plants they 

 are not yet differentiated, and, as far as these belong to 

 the Phycochromacese, the whole non-nucleated protoplasm 

 of the cell, according to Schmitz, is stained.^* But later 

 Hansgirg demonstrated nuclei and chromatophores in 

 some algae of this group.^^ From the Chlorophycese up- 

 ward they are universal in the green plants. In the higher 

 plants, where they were discovered by Schimper,^^ they 

 are usually colorless in young cells. As a rule they re- 

 main so in the underground parts, which are normally not 

 exposed to light. 



Phylogenetically, therefore, plants with undifferen- 

 tiated colored protoplasm are probably older than those 



32Schmitz, F. Die vielkernigen Zellen der Siphonocladiaceen. p. 

 27. 1879. 



s^Van Beneden et Julin, La spermatogenese chez I'Ascaride me- 

 galocephale, Bruxelles, 1884. 



34 Schmitz, F. Die Chrom<itophoren der Algen. p. 9. 1882. 



35Hansgirg, A. Ber, Deut. Bot Ges. 3: 14. 1885. 



ssSchimper, A. F. W. Ueber die Entwickelung der Chlorophyl- 

 korner und Farbkorper. Bot Zeit. 41: 105, 121, 137, 153. 1883. 



