1892.] MICKOSCOPICAL JOUKNAL. 63 



Radiolaria: Their Life-History and Their Classification. 



By Rev. FRED'K B. CARTER, 



MONTCLAIR, N. I. 



[Read before the Department of Microscopy, Brooklyn Institute, February 16, 1892.] 



For the life-history in general of the Radiolaria the i-eader is referred 

 to the article on the Rhizopoda in the number of this periodical for 

 Januar}', iSSS. In the main, the structure corresponds ; that is to sa}', 

 the essential part of the Radiolaria, as of all the other rhizopods, is the 

 protoplasmic substance^ and the action of this substance is the same in 

 all. There is the same formation of pseudopods, the same use of 

 them. Digestion and assimilation are effected in the same manner. 

 It only remains therefore to point out certain features wherein the Ra- 

 diolaria diff'cr from the other orders of the rhizopods. 



One of the most important is the absence of the contractile vacuole. 

 This is never present in these forms,* and it alone distinguishes them 

 from the fresh-water rhizopods ; but there is a still more important dif- 

 ference, namely, the presence of a mefnbranous ceittral capsule sunk 

 in their protoplasm. This, says Lankester (in the Ency. Brit.), makes 

 them a very strongly-marked group, definitely sepai^ated from all other 

 rhizopods. This capsule is a perforated shell of membi-anous con- 

 sistence, having protoplasm within it which is continuous through the 

 pores or apertures of the capsule with the outer protoplasm. That is 

 to say, in the other shelled rhizopods the main body of the protoplasm 

 is all ivithin the shell, but in this group it is outside as well as inside. 



And this leads to the third distinction, which is the possession of a 

 skeleton in addition to the inner shell. The fresh-water rhizopods, 

 then, and also the Foraminifera group of the marine rhizopods, pos- 

 sess a shell, but the Radiolaria both shell and skeleton^ and between 

 the shell and skeletofz there is a mass of protoplasfn such as does not 

 exist outside the shell of the other groups. The skeleton^ then, is 

 peculiar to these forms and deserves close attention on that account 

 alone ;. but not only on that account, for it has an intrinsic value because 

 of the wonderful beauty and variety of its shapes. " No other group of 

 organisms," saysHaeckel, " develops in the construction of their skeleton 

 such a variety of fundamental forms with such geometrical regularity 

 and such elegant architecture" (Leidy, Rhizopods). And a glance at 

 Haeckel's inagnificent plates, in his elaborate monograph on this group, 

 is sufficient to show what an inexhaustible feast there is here for the 

 eyes of the careful observer. " Sometimes," says Leidy, ''it consists 

 of a simple trellised ball, sometimes a series of several such balls, enclosed 

 concentrically in one another, and connected together by radial bars. 

 Generally delicate spines, often branching, radiate from the surface of 

 the balls. In other instances, the skeleton consists of a star mostly com- 

 posed of twenty spines, arranged in definite order and united in a com- 

 mon centre, or it is a delicate, many-chambered cell, as in the Foram- 

 inifera. 



Preparation. — Procure a small lump of Barbadoes earth. Before 

 you break it up note, by the way, how light it is. I had a lump 

 which was a little over an inch square. It weighed but half an ounce, 

 or 240 grains, and yet it contains thousands and tens of thousands of 



♦Ency. Brit., Art. Protozoa. 



