246 Papers from the Department of Marine Biology. 



cells, as a centrifugal force, in directions at right angles to the dorso- 

 ventral direction and also in the ventro-dorsal direction or the reverse 

 of the natural pull of gravity. In practically all cases the proper 

 controls were secured and it soon became apparent that this force 

 might be the main cause of the orientation. By referring to the table 

 it will be seen that 5 experiments were performed on torpedoes Nos. 8, 

 9, 3, 20, and 4. Also, it can be seen that the forces applied to the 

 tissues were, in terms of gravity, for torpedo No. 8, 1 time gravity in 

 reverse direction to nature for 8 days; for torpedo No. 9, 40.6 times 

 gravity for 2 minutes at right angles to force of gravity in nature; for 

 torpedo No. 3, 543 times gravity for 2 minutes at right angles to 

 gravity in nature; for torpedo No. 20, 601 times gravity in reverse 

 direction to nature for 30 minutes; for torpedo No. 4, 828 times gravity 

 at right angles to nature for 30 minutes. 



Thus we have a series of 5 experiments ranging from the natural 

 force of gravity reversed and applied for 8 days up to 828 times gravitj' 

 applied for 30 minutes. 



The first experiment of this series, on torpedo No. 8, yielded no 

 visible results. In this case we had a small fish to deal with, which 

 somewhat lessens the value of the experiment. No orientation ap- 

 peared in the brain as a result. Thus the questions are left open: 

 Did any orientation exist in a ventral direction which had been nullified 

 by the experiment? And, would a result have appeared if the fish 

 were larger and had possessed a natural orientation? Another experi- 

 ment of this nature should have been tried on a larger fish, but the 

 two questions can still be answered, I think: the first by the state- 

 ment that all small fish possess no orientation, or very little, and the 

 second by a similar experiment performed on an adult Tetronarce occi- 

 dentalis, to be described in another paper, in which the plasmosomes are 

 always oriented sharply in the ventral position. The same experiment 

 performed on this large fish showed that gravity alone could not move 

 the plasmosome in 7 days in this adult form. 



Turning to experiments on torpedo No. 9, we find that we are dealing 

 with a 16 cm. fish, which is small, but not as small as torpedo No. 8. 

 The control made in this case shows that a considerable amount of 

 natural orientation was present, about 15 per cent. The force applied 

 as a centrifugal force by the centrifuge was low compared to the later 

 experiments, but high compared to gravity, being a little over 40 times 

 that measure. The time was 2 minutes and perhaps should have been 

 longer to show a complete negation; still, since some of the later 

 experiments with stronger forces were also of short duration, we can 

 feel satisfied that real results are being secured and real comparisons 

 being made. The results in this example were completely negative, 

 showing that when 40 times the force of gravity is applied for 2 minutes 

 the contents of the nucleus remain undisturbed. 



