1880.] 



MICKOSCOPICAL JOUKNAL. 



43 



parts of the animal ; in the cortical 

 portion, minute particles may be 

 seen in very slow movement with 

 the sarcode current. 



Dr. Joseph Leidy has observed 

 the pseudopodia entirely with- 

 drawn, leaving no axes, and he has 

 also seen them extend again in 

 other localities, where no spines 

 previously existed. Moreover, the 

 axes of the rays have been sub- 

 jected to the action of various 

 acids, and in all instances they have 

 disappeared. 



The nuclei are said to number 

 rather more than one hundred (ac- 

 cording to Carter four hundred). 

 Schulze and Schneider have inves- 

 tigated the reproduction. Accord- 

 ing to their observations, as the 

 period of reproduction approaches, 

 the medulla becomes darker in 

 color, and more distinctly separated 

 from the cortical ]3ortion ; the axes 

 and pseudopodia are withdrawn, 

 and the animal becomes enveloped 

 by a gelatinous secretion ; binary 

 segmentation follows, each seg- 

 mentation-sphere possessing its own 

 medullary and cortical layers ; the 

 cortical region becomes converted 

 into a firm investment, by the depo- 

 sit of a silicious covering, and this 

 condition attains throughout the 

 winter; in spring this hard, invest- 

 ing layer is lost, and the contents 

 appear as young forms of Actinos- 

 phceriiim, afterward the nuclei in- 

 crease in number. 



Cell - multiplication in Clian- 

 transia Violacea, Ktz. 



IV. The genus Chantransia, 

 among the fresh-water Algse, is re- 

 presented in the United States by 

 the following five species which 

 have come under my observation : 

 C. macrospora, Wood, found spar- 

 sely by Mr. Ravanel in South Caro- 

 lina, but more recently, in August, 



1879, in large quantities, by myself 

 in a pond at Atsion, New Jersey. 

 It is the largest of our forms, and 

 is a beautiful plant. C. Ilermanni, 

 Roth, was collected by Dr. Beard- 

 sley, attached to Lemanea in a 

 stream near Painsville, Ohio ; an- 

 other large form, I have named G. 

 Beardsleyi^ from the same locality. 

 C. pygmea, Ktz., from Florida, 

 collected by Capt. D. D. Smith; 

 C. violecea, Ktz., and C. expansa, 

 ^ood, a variety of the former are, c*^, 

 not unfrequent here. Fig. Id A 

 alf ords a general idea of the features 

 of the plants of this genus ; the 

 color is usually steel-blue or pur- 

 plish, sometimes yellowish-green 

 while growing, but it changes to 

 purple when mounted and dried 

 and the plants are easily recognized. 



The object of this paper is not 

 to describe the plant, but to draw 

 attention to a feature of propaga- 

 tion by cell-multiplication, a process 

 apparently not well understood or 

 even recognized, yet a most impor- 

 tant and characteristic feature in 

 the life-history of many of the 

 lower forms of Algge. 



A singular facility for the study 

 of the development of Chantransia 

 violacea, Ktz., presented itself in 

 my aquarium. The plant has been 

 growing there for the past three 

 years. The glasses frequently be- 

 come dimmed by the multiplication 

 of spores, and the profuse growth 

 of the plant. The tetraspores scat- 

 tered abundantly from the terminal 

 cells {h b b b) of the hlaments, 

 float about in the water until they 

 find a suitable spot whereon to 

 attach themselves for propagation. 

 The scratches in the glass appear to 

 be the most advantageous places 

 for the reception of the spores. 

 Fig. 13 C C represents such a 

 scratch in which a few spores have 

 collected, probably only one at each 

 of the points indicated by the upper 



