ELISHA MITCHELL SCIENTIFIC SOCIETY. 89 



were to be found of this size and appearance, and hence it 

 was not necessary to watch the development of this sino^le 

 individual longer, as other fields promised better results. 



There was almost an unlimited supph' of heliazoa inter- 

 mediate in size between the two whose union produced the 

 one just mentioned. They differed in no respect from one 

 another or from the two just mentioned, except a slight 

 difference in size, and every gradation between them was 

 to be found. Merely for the sake of filling up the gap 

 which exists in regard to size between the two individuals 

 whose union we just referred to, I will cite one example 

 out of many which I have observed. Two similar indi- 

 viduals, slightly larger than the smaller (Fig. 26) of the 

 two just united were seen to come together (Fig. 22), and, 

 as a result of their union, a heliazoan was produced so nearly 

 like the larger (Fig. 25) of the two of the former indi- 

 viduals, that there was practically no difference between 

 them. 



Another field was now chosen in which were a number 

 of heliazoa, similar in all respects to the one representing 

 our last stage (Fig. 7). I had not waited long before it was 

 evndent that two of these animals were gradually approach- 

 ing one another from some cause which I was unable to 

 discover. When wnthin a very short distance, in fact, 

 almost ready to meet, there occurred a very singular move- 

 ment on the part of both individuals — a movement w^hich 

 I can hardly account for — in which there was produced a 

 swelling, as it were, in that part of the sphere of both 

 animals (Fig. 8, 9) which was just about to touch the 

 other, and by continued enlarging with increased rapidity 

 soon met one another, thus uniting the two individuals 

 much more quickly than they otherwise would have done. 

 Immediately upon touching one another the at first narrow 

 neck uniting them rapidly enlarged (Fig. 10), the proto- 

 plasm of the one flowing into the other and vice versa until 



