The President's Address. By the Rev. W. H. Dallinger. 205 



hyaline, and with just one point a, fig. 19, plate VIII., -which is the 

 last trace of the fusion. The nucleus, however, can be seen, as the 

 figure shows ; but with no discoverable structure, and only made 

 visible with careful handling of light and lens. 



Now if this blended nucleus be carefully watched in the living 

 state, it will be seen to difi'use itself radially through the body- 

 sarcode of the blended organism as seen in plate VIII. fig. 20, until 

 every trace of the nucleus is gone ; and the still globule of living 

 matter becomes tight and glossy, but no trace of structure can be 

 anywhere found in it. It remains in this condition for six hours, 

 and as detailed in my former papers, bursts, pouring out immense 

 numbers of minute germs (plate VII. fig. 7). 



The other nucleated form of these organisms that I have suc- 

 cessfully followed through the whole succession of continuous 

 fissions into conjugation, is D. Drysdali. It is in this respect an 

 extremely remarkable form. 



In my account of this organism before the Koyal Society,* I 

 recorded that nine separate forms were followed at difi^erent times, 

 from the first fission after maturity had been attained, through all 

 successive fissions, to what was in each case the last. There were 

 from seven to eight acts of fission in an hour, for the first four 

 hours, and about five per hour during the next two hours, and then 

 longer intervals ensued. But when the segmented organism was 

 followed, as of course it could only be, in one division of each 

 fission, and every link in the chain was thus completed, the one 

 which was the product of the last act of fission died in six cases, 

 but underwent metamorphosis preliminary to conjugation in three 

 cases. 



In the latter, almost immediately after the fissional act was 

 completed, an amoeboid condition, which is quite unknown in any 

 other stage of its life-history, supervened. The aspect of the 

 organism in this condition is seen in plate IX. fig. 8, where it will 

 be seen that this organism, shown in nearly its normal state at 

 fig. 5, ibid., is curiously amoeboid throughout its sarcode, and that 

 the trailing flagella a a have become *' clubbed," and are fusing with 

 the body ; while the nucleus h has greatly increased in size and has 

 become white. The changes are now very rapid ; not more than 

 seventy seconds elapse before the trailing flagella are wholly fused 

 with the body-substance, and while the head-and-neck-like pro- 

 tuberance characteristic of this organism is retained, the body, 

 having lost its trailing or lateral flagella, becomes oval, with an 

 immensely developed nucleus, as seen in plate IX. fig. 9. In this 

 state it swims with ease ; and now a band of granules is formed as 

 shown at fig. 9 a, and it swims into the midst of the closely 



* Proc. Roy. Soc, xxvii. (1878) p. 336. 



