The Microscope. 355 



nature. It is nothing but a minute spherical mass of finely granu- 

 lar and hyaline protoplasm, 14.5 ,« in diameter, with a contained 

 nucleus and a distinct nucleolus (Fig. 1). In appearauce, it resembles 

 ■white blood -corpuscles, with a distinct and sharply defined nucleus. 

 Later, however, a vacuole appears in its substance, and, increasing in 

 size, often becomes larger than the original mass of protoplasm, so 

 that the latter forms but a thin layer surrounding it (Figs. 2, 16, 12). 

 In this stage a pseudopodium or ray may be present (Fig. 12). 



Two heliazoa of the first stage were seen to come together, which, 

 however, as in nearly all cases, was due to the agitation of the water 

 by the worms, and, immediately upon touching one another (Fig. 23), 

 to fuse and run together, just as a drop of water fuses with another 

 drop of water. It is impossible to say which of the two was 

 devoured; both appeared to play an equal part, the vacuole and 

 nucleus of both being present, and the whole immediately assuming 

 a spherical form, and appearing (Fig. 3) much like any one of the 

 two of which it is now composed, except that it has two vacuoles and 

 two nuclei. In the course of five minutes this yoitng two-vacuoled 

 heliazoan had developed a ray, and in its interior the characteristic 

 axis thread could be distinctly seen (Fig. 20). The absence or the 

 number of rays when present in the young heliazoa is of no special 

 value, and varies with different individuals of the same age, as will 

 be seen from the figures. 



Whether this fu.sion of two individuals of the same species be 

 called eating or not, does not concern us, and I sha]l not attempt to 

 discuss the subject here. As a matter of fact, however, it is not con- 

 jugation for purposes of reproduction, or rejuvenescence, as will be 

 seen later; and, since we have these animals developing by this 

 method of increase, as well as by that of an undoubted eating of 

 other animals, it matters not, so far as development is concerned, 

 whether they appropriate material so near like that of their own 

 bodies that it needs no change to form a part of them, or whether the 

 food bo different, and, hence, have to be changed or digested before 

 it can be so appropriated. I have observed farther advanced 

 heliazoa capture infusoria and amoeba and surround them, and draw 

 them into their interior, where they remained to be digested; and at 

 the same time I have observed those same heliazoa capture other 

 heliazoa, and, instead of drawing them into their interior and sur- 

 rounding them, as they did other bodies, they would draw them in 

 until the two heliazoa touched, when there occurred a fusing and 

 blending of the two animals into one, just so much larger. My only 



