TRANSFORMATION OF HELIOTBOPIO ANIMALS 



become positively heliot ropic. Later, when the temperature 

 again rose, they again became negatively heliotropic 



The addition of 80 parts of fresh water to 100 parts of 

 normal sea-water made positively heliotropie Copepods nega- 

 tively heliotropie; the addition of (>0 percent, of fresh water 

 made a number of them negative, and a smaller addition 

 had little or no effect. 



Almost all negative Copepods became positively helio- 

 tropie when introduced into sea-water to which 1.5 g. of 

 XaCl had been added to each 100 c.c. of sea-water. After 

 the detailed description of the behavior of the Polygordius 

 larvse these statements may suffice. 



7. I have already shown in my earlier papers on heliot- 

 ropism that there is scarcely a heliotropie reaction in plants 

 which cannot also be demonstrated in animals. This fact is 

 again corroborated by the phenomena which we have de- 

 scribed here. I quote the following from Strassburger's 

 well-known investigation on the effect of light and heat 

 upon swarm spores: 1 



'When I had [Hsematococcus] swarm spores before me which 

 had collected, at the ordinary temperature of the room in which 

 I worked (16-18 C.) at the positive edge of the drop, I was sure of 

 being able to transfer them to the negative side of the drop, at the 

 same light intensity, when I exposed the preparation to a tempi -ra- 

 ture of about 1 C. At this low temperature almost all of them 

 went to the negative edge of the drop. On the other hand, I was 

 alim>--t as certain to find the most negatively heliotropie H;emato- 

 coccus swarm spores at the positive edge of the drop when I 

 exposed the preparation to a temperature of about ."."> C. 



Only in the sign of heliotropism is there a difference in 



tin ell'ect of heat on Hsematococcus swarm spores and Poly- 

 gordius larva- and Copepods. I consider it possible that 

 animals may be found which become negatively heliotropie 

 when cooled. Massart" found similar phenomena in Klagel- 



i Jena, 1873, p. 56. 

 J i w tL&.B&&B.T, Bulletin de I 'Academic roy ale de Beige, \< l.XXII 'l.v.U). 



