126 



HARDWICKE'S SCIENCE-GOSSIP. 



erect cylindrical spine, every hole being consequently 

 surrounded by a circlet of six spines ; by the perfect 

 regularity of the lattice-work of its shell ; and by its 

 comparatively thick and unbranched pseudopodia. 

 The little-known Hedriocystis pcllucida of Hertwig 

 forms in all probability a third species of the same 

 genus. The class Heliozoa has been divided into 

 four orders : Aphrothoraca, Chlamydophora, Chala- 

 rothoraca, and Desmothoraca, to the last of which 

 Clathrulina belongs. . . . C. clegans is here for the 

 first time recorded from the continent of Asia." 



My sketches which illustrate this paper will suffi- 

 ciently show the main features of Clathrulina. It is 

 a delicate unicellular organism allied to the sun ani- 

 malcule, but is enclosed in a siliceous sphere ; in 

 my experience the carapace is not always absolutely 

 spherical. The organism bears a close resemblance to 

 the marine Radiolaria. In young specimens the sphere 

 is hyaline ; in the older specimens it is a yellowish 

 brown. Unlike Actinophrys sol, the sarcode body 

 of Clathrulina is irregular in form. It has a nucleus, 



C.Vf 



Fig. 79. — C. clegans. (D), Protoplasmic contents undergoing 

 encystment at>; all threadlets withdrawn. 



contractile vesicles, and food vacuoles. The pseudo- 

 podia, which are of great tenuity, radiate as in Figs. 

 76, 77, 78, A, B, and c, through the latticed openings 

 of the shell in all directions. In an active specimen, 

 like C, the protoplasmic body appears to invest the 

 sphere with a delicate veil, beyond which the ordi- 

 nary pseudopodia extend. Assimilation of food par- 

 ticles has been observed to be occasionally performed 

 outside the siliceous capsule, by an afflux of proto- 

 plasm to the pseudopodia on the side where the par- 

 ticle may be arrested ; but as a rule the observations 

 show that this function is carried on within the sphere. 

 Specimens are frequently met with in which, as in E 

 (Fig. 80), the sarcode body is retracted on all sides 

 into the capsule. Reproduction is carried on in three 

 ways : (1) By fission into two parts, which on quit- 

 ting the shell, put forth pseudopodia, develop a stem, 

 and finally silicify the protoplasmic foundations of 

 the capsule and stem, siliceous salts being apparently 

 taken up by the organism, and deposited on the 

 exoplasm ; (2) By fission into several parts, which 

 instead of quitting the shell as amcebulce, become 

 encysted ; after the winter's rest, each) cyst de- 

 velops a free-swimming zoospore, furnished with two 



flagella, which is ultimately transformed, as men- 

 tioned under the succeeding head, into the perfect 

 organism ; (3) By fission into three parts, one of 

 which again subdivides into two ; these latter force 

 their way through the lattice-work of the capsule, 

 swim about as free flagellula; for a short time, 

 and thereafter fix themselves, take on a globular 

 form, develop pseudopodia, and later on a siliceous 

 capsule and stem, the sarcode being ultimately with- 

 drawn into the body-substance of the core. The 

 second and third methods are obviously best suited 

 to secure dispersal of the species. I am indebted for 

 these particulars to Mr. Wood Mason's paper already 

 referred to, and which has been mainly drawn up from 

 the memoirs of Cienkowski, Greef, and Hertwig and 

 Lesser, and from Biitschli's account of the Heliozoa. 

 In Fig. 79, D I have represented what I believe to 



Fig. 80. — C. elegayis. (E), protoplasm retracted. In this and 

 the preceding figure the objective is focussed on the proto- 

 plasmic core of the organism, and the carapace is seen in 

 outline, the lattice-work not being in focus. 



have been a reproductive process in course of pro- 

 gress, in one of the specimens secured by me. The 

 pseudopodia were withdrawn on all sides, while a 

 portion of the protoplasmic contents were protruded 

 in a dense stream, the further extremity of which 

 seemed to be encysting itself outside the capsule at y. 

 A large vacuole had formed near the point of origin 

 of the stream, and the contractile vesicle was in vigo- 

 rous action. I could not detect the nucleus, though 

 there were four or five small patches of condensed 

 granular matter in the body of the specimen. 



The water in which I found my specimens had 

 been drawn from the General's Tank quite a month 

 previous to my discovery. The Clathrulinas were 

 attached to decaying portions of Anacharis and 

 Vallisneria, and were also mixed up with the debris at 

 the bottom of the glass bowl containing the weeds. 

 In all my sketches I have shortened the stems, which 

 in length are from six to seven times the diameter of 

 the capsule. The scale appended to the sketches 



