46 SYNOPTIC COLLECTION. 



inherited character. The variability of this organ in the 

 intermediate forms, and the close connection between the 

 Heliozoa and Mastigophora are shown in the extremely 

 interesting transitional organism, Dimorpha mutans Gru- 

 ber, 1 to which we have already referred. When first 

 observed the animal ajppeared to be an Amoeba radios a 

 or a Heliozoan, but suddenly it fell into a trembling 

 motion and a long whip was thrown out. PL 50, figs, i 8, 

 show the changes undergone in about two hours. In 

 fig. i the animal is leaving the Heliozoan stage, the body 

 is still spherical, but the pseudopodia are short and one 

 long whip begins to strike the water. The next moment 

 the body is extended lengthwise and becomes egg-shaped. 

 The pseudopodia shorten themselves still more, and the 

 Dimorpha begins to swim propelled by two long whips. 

 At times one of the whips beats the water while the other 

 trails behind (fig. 2). Suddenly the animal stops swim- 

 ming and turns the forward end of its body downward 

 while the whips feel about on the bottom (fig. 3). All 

 movements cease, the body becomes spherical and frcia 

 every side fine ray-like pseudopodia are thrust out (fig. 4). 

 But the Dimorpha seems not satisfied with the spot it has 

 chosen, or it is disturbed in some other way, for the above 

 described transformation occurs again (fig. 5), and the 

 body becomes quite smooth during its rapid swimming 

 (fig. 6) . The little sun-animal has transformed itself 

 into such a perfect whipped creature that it is difficult to 

 keep track of it among the other flagellate organisms in 

 the water. After swimming about it comes to rest again 

 (fig. 7), "thrusts out its pseudopodia, and transforms itself 

 in a few moments into a Heliozoan (fig. 8). Fig. 9 repre- 

 sents the Dimorpha in its usual condition. The body is 

 pointed at the posterior end where the food elements 

 are crowded closely together. Gruber. to whom we are 

 indebted for the above description, tried various experi- 



iZeitschr. f. wiss. Zool., XXXVI, 1882, p. 445. 



