70 W. ARCHER. 



and a granular posterior end (PI. XXII, fig. 2S) . In the former 

 could be seen the nucleus with its nucleolus, almost com- 

 pletely filling it, and in the latter two or three contractile 

 vacuoles ; at the anterior apex appear two flagella as long as 

 the body, by means of which the organism advances with a 

 slow and uniform rotating movement. After about half an 

 hour or more it settles down vertically on some object, where 

 to develope its stipes, and whilst assuming a globular figure, 

 continues, without advancing, to rotate on its longitudinal 

 axis. As soon as this has ceased the pseudopodia become 

 quickly developed on all sides, and the hotly passes into the 

 form of a naked Clathrulina. About this time the stipes 

 becom.es apparent as a clearly-shining, sharply-contoured 

 circle on the surface of the body (PL XXII, fig. 24, s). If the 

 organism be brought into a profile view, it is seen that the 

 stipes which becomes firmly attached to the substratum, 

 soon growing to a considerable size, takes its origin in an 

 umbilicus-like depression of the body and forms a direct 

 process of the body-mass (Fig. 25). It thus originates 

 as a protoplasmic structure and only subsequently becomes 

 developed around it the tubular skeleton- portion of the per- 

 manent stipes. In the progress of growth the protoplasmic 

 prolongation filling the tube must become retracted, for in 

 the fully-formed Clathrulina the soft body-mass stands no 

 where in connection with the stipes. 



The authors were not able to follow out the development 

 of the fenestrate skeleton, but doubtless it is preformed by 

 protoplasm, they at least found that some young individuals 

 still naked, but with stipes, showed the pseudopodia mutually 

 united by transverse connections ; these forming, at a little 

 distance from the body-surface, beautiful arcades, most pro- 

 bably the bases for the development of the future fenestrate 

 skeleton. 



Reverting to the larger subdivided portion of the original 

 body-mass left behind within the shell, and which at first 

 maintains its place therein, still displaying its numerous 

 pseudopodia as if it were making an endeavour to make good 

 the loss in body-substance which it had suffered, the authors 

 arrived at no definite results. In one caseof Avhich they had 

 under observation, the object died from want of accession of 

 a fresh supply of water, after they had had it for a whole 

 day long under observation, without any perceptible altera- 

 tion. On another occasion they foimd the shell empty, on 

 renewing their observations on the following day, but as 

 they saw two zoospores hovering near they supposed that the 

 body left behind (as described) had once more subdivided, and 



