The President's Address. By the Bev, W. H. Dcdliriger. 193 



a turbinated shape e, which is at once followed by quick and 

 continuous internal movement, which results in the breaking up of 

 the mass into a condition shown at /, where there is no trace of 

 investing membrane, and the parts are in a state of movement upon 

 each other for some twenty minutes, when the whole breaks up into 

 perfect, but minute adult-shaped forms, with complete power of 

 motion, as at g. 



In fig. 4, a is the adult form. It is always invested with a 

 hyaline coat ; after swimming for awhile the interior sarcode con- 

 stricts as at c in & ; the constriction deepens, as at e in (? ; and 

 the two halves separate within the membrane, as two oval bodies, 

 g, h in /. Subdivision goes on rapidly within, until sixteen perfect 

 oval bodies vnth minute flagella lie within the mother body, and at 

 length break the investment and go free. 



Here we have the same result accompHshed, with and without 

 an investing envelope : and in both cases after a long-continued 

 increase by each individual thus separated by fission, there is a 

 perpetuation of the form by a fertihzing process and spore. 



There are two other forms that present remarkable phenomena 

 in self-division. They are shown in figs. 5 and 6. 



In a, fig. 5, we see the common condition of the largest of the 

 septic organisms I know. In the course of a few minutes, if 

 followed, it is seen to lose its sharpness at the end opposite the 

 flagella, and is amoeboid, in the course of a couple of minutes 

 presenting an appearance shown at h. The amoeboid condition is 

 seen at d, but in this state the root or base, out of which the four 

 flagella spring, divides, and two pairs of flagella, each independent 

 of the other, recede from each other, and the nucleus partially 

 splits, as at c. The amoeboid condition in a short time ceases, as 

 at e, the flagella rapidly recede from each other, and the nucleus 

 almost wholly divides, seen at e,f; at this point there is a sudden 

 flattening of the organism from before backwards, and a lateral 

 lengthening, as at g ', the flagella still recede, as at h, i, and a con- 

 striction appears, as at h. Soon the flagella are at opposite poles, 

 and pull against each other; the neck of sarcode is drawn out, 

 as at I, and with it each half of the nucleus into its separate part. 

 A moment or two after it has reached the state shown at I, a 

 vigorous movement snaps the union, and two perfect forms are 

 free. 



The other and final instance is seen at a, fig. 6. The form has 

 an anterior and two lateral flagella, and swims with supreme 

 grace. 



The first indication of fission is a delicate slit in the anterior 

 knob of the body h, and with the opening of this the front flagellum 

 splits. 



Ser. 2.— Vol. V. o 



