244 Journal of Applied Microscopy. 



of it. In that case the motion is merely repeated, and if immersed in the fluid 

 the animal will continue to turn for ten minutes or more. 



All negative stimuli produce the same reaction. No intelligence is shown. 



Prof. Herrick added the observation that paramcecia raised in his laboratory 

 near a radiator, for about one hundred generations, were positively thermotropic 

 to a temperature of 70 degrees, 24 degrees being about the normal temperature. 



Dr. S. Watase, in his paper on the " Characteristics of Mitosis and Amitosis," 

 reviewed the literature of the subject up to the present date, and added the results 

 of his own studies. 



Mitosis may occur in many different ways. The spindle may originate inside 

 of the nucleus and then migrate out, or it may originate outside of the nucleus. 

 Great variation may be found in the same family. There may be division with- 

 out a centrosome, or there may be a centrosome alone, or there may be neither 

 centrosome nor spindle. 



The characteristics of mitosis are neither the spindle nor the centrosome ; 

 these are only accessory, but the essential features consist in the special arrange- 

 ment of chromatic substance in rods or chromosomes, and in increased nucleic 

 acid. These changes always occur, while in amitosis the character of the chro- 

 matin is not changed at all and nucleic acid is not present. 



He considers that the two types are distinct and independent, although they 

 may exist side by side, as for example, in the fish egg, where the blastoderm may 

 divide by mitosis while the periblast divides by amitosis. The karyokinetic cell 

 no longer belongs to any tissue, as brain, muscle, etc., but is embryonic or proto- 

 morphic in character. 



Amitosis is the homologue of fission and asexual reproduction, and in this 

 the acquired characters would be retained by the new individual. 



Mitosis is the homologue of sexual reproduction. Here acquired characters 

 are eliminated and the new organism may take up any line of development. 



A paper by H. W. Rand, on " Regeneration and Regulation in Hydra viridis," 

 was read. Since the Hundred-headed Hydra of mythology, this animal has been 

 renowned for its power of overcoming any inconvenience that might be caused 

 by the loss of parts of its corporeal entity. From the experiments performed it 

 was found that the upper half of the hydra was less active than the lower half in 

 regeneration. Growth is apparently controlled by a law of symmetry, for the 

 right number of tentacles is always regenerated whatever the mutilation 

 may be. 



The same thing was shown by Dr. A. E. Verrill in the starfishes. He had 

 observed thousands of mutilated starfishes, and exhibited specimens showing the 

 symmetrical regeneration of lost parts. 



Dr. Verrill also showed specimens and drawings of the fauna of Bermuda, 

 among which were actinians that place their ova in pockets on the outside of the 

 body, where they develop. He called the attention of the society to the great 

 desirability of establishing a Zoological station at Bermuda. 



A paper by Prof. C. F. Hodge, on " Possible Amoeboid Movements of the 

 Dendritic Processes of Cortical Nerve Cells," was received with interest Much 

 attention has been paid to the condition of nerve cells in their relation to mental 



