SEXUAL PHENOMENA IN THE PROTOZOA 



223 



or even longer without any special occurrence. Then the scene sud- 

 denly changed. Happening all at once in the vicinity of an attached 

 Vorticelta, a bud quickly changed its direction with a jerk, and 

 approached the larger form, fluttering about it like a butterfly over a 

 flower, and gliding over its surface here and there as though tasting. 

 After this play, repeated upon several individuals, had gone on for 

 some minutes, the bud finally became firmly attached." Again : " I 

 observed another performance still more remarkable from its physio- 

 logical and particularly from its psycho-physiological significance. 

 A free-swimming bud crossed the path of a large Vorticella which 

 had become free from its stalk in the usual manner and which was 

 roaming about with great activity. At the instant of the meeting 

 — there was no trace of a pause — the bud suddenly changed its 

 direction and followed the Vorticella with great rapidity. It developed 

 into a regular chase which lasted about five seconds, during which time 



s— 



Fig. 121. — Conjugation in Lagenophrys ampulla St. [BUTSCHLI.] 

 s. Microgamete attached to normal cell (A). B. Fusion of macro- and microgametes. 



the bud remained about one-fifteenth of a millimeter behind the Vor- 

 ticella, although it did not become attached, for it was lost by a sudden 

 side movement of the larger form. The bud then continued its way 

 as before. These processes are remarkable, since they demonstrate a 

 fine and rapid perception, a rapid and safe will determination, and 

 finely divided motor innervation. They show to what astonishing 

 height and multiplicity physiological differentiation in animals can go, 

 even within a single cell." 1 



The phenomena which Engelmann observed and regarded as 

 evidence of psychic activity, have been shown to owe their origin for 

 the most part to chemical and physical stimuli. But the sex-differ- 

 entiation indicated by the diversity in size and activity of the gametes, 

 and the fusion of the two cells which he described, are typical of fer- 



1 Loc. cil, p. 583. 



