■E r 



THE GKNVS CHLOROCHYTRIUHr'. 



17 



only be regarded as an amended description of Wright's species, tliongh 

 there arc several conspicuous differences between the two. The general 

 characters of the cells exactly correspond to those of Wriglit's species, but 

 Lagerhoim's figures indicate a greater variety in the shape of the cells. 

 There is a single parietal chloroplast which is frequently irregular in shape 

 and contnins ouc conspicuous pyrenoid. 



The most Important differences between the descriptions of these two 

 forms are that in AYriglit's form tliere are two kinds of uniciliate zoogonidia 

 formed by simultaneous division of the mother-cell contents, whereas in 

 Lagerlieim's form the zoogonidia are produced by a successive bipartition of 

 the niotlier-cell contents ; all are small and biciliate, and they fuse in pairs 

 to form (piadricih'ate zoo/ygotes. Wright's record of uniciliate zoogonidia 

 of two sizes is certainly the n'sult of incorrect observation^ and it is quite 

 possible that tlio hirger kind were zoozygotes formed by the fusion of the 

 smaller zoogonidia, as in Lagerheim's form. Again, it has been directly 

 observed that in ChlorofJtf/lrluni gmnde division of the cell-contents may take 

 place both by free cell-formation and by successive bipartition, though in 

 botli cases the nucleus divides by successive bipartition. It seems, therefore, 

 to be a matter of small importance whether the cytoplasm divides up con- 

 currently w^ith the bi})artition of the nucleus^ or whether it remains until the 

 divisions of the nucleus are completed, and then rounds itself off simul- 

 taneously iitto as many portions as there are daughter-nuclei in the cell; 

 especially since no cell-walls arc formed during the process. It is just 

 possiljle that the two different methods of division may be induced by 

 varying external conditions, though there is no proof of this ; hence such a 

 lifference cannot be considered of specific importance by itself. 



In L885, Reinh:irdt* found an alga on the shores of the Black Sea, in the 



( 



tubes of Cotarnariam^\Y\n(^\\ lie consitlered to be identical with that described 

 by Wright. He described the chloroplast as a lateral plate lying on one 

 side of the cell, containing a single pyrenoid and produced at its edges into 

 a nuinber of radiating arms. Zoogonidia-formution took place by free 

 cell-division in Ihis material. Reinhardt considered that the shape of the 

 chronnitophore and tlu^ free cell-division w^ere characters of sufficient 

 importance to justify his establishing a new genus Cldorocystls^ wifli this 

 species as a basis, differing from CldotHu'liyLruini on just th(;se two points, and 

 he renamed the alga CIdorocystU CoJuui (E. P. Wright), TIeinhardt, Recent 

 work by West and Gardner f has shown that Reinbardt's establishment of 

 this genus was entirely unjustified, and Wright's name has been restored. 



Gardnor, however, does not consider that Wright and ReinharJt were 



* Reinhardtj L. *Coiitiibutiones ad niorpliologiani et systematical:! algaram Marl 



Ni-ri/ Odessa, 1885, 



t Gardner, N, L. Uniw Calif. PuU. in r»otanv, vol. vi. June 11)17. 



LINN. JOUKN. — BOTANTj VOL. XLV. C 



u * 



