BIOLOGICAL INVESTIGATIONS. 149 



Brauer of Vienna, accustomed to the study of the adaptation 

 of organs among insects, and the author of this lecture, accus- 

 tomed to look for internal factors from a more theoretical point 

 of view, agree in criticising these results as defective, because 

 they did not take into account the fact that the amount of salt 

 may have had no direct effect, except in so far as it increased 

 the density of the fluid in which the animals moved. The fact 

 that the modifications took place mainly in the abdomen, and 

 that the increase in hairiness, and in length and size of this 

 part, and variations of the appendages as the water decreased 

 in density, can be just as probably attributed to the extra 

 growth caused by increased efforts necessary for breathing 

 and swimming in a more rarified medium. Whether this 

 objection be true, or the reverse, does not matter here, since 

 it is simply introduced to show the need of considering the 

 organism as a vitalized body which is capable of reacting from 

 within appropriately in response to external stimuli. Experi- 

 ments that do not take this essential condition into serious 

 consideration are open to similar objections. 



In order to prove a physical cause acting wholly and directly 

 from the outside, the internal reactions of the organism should 

 be shown to be passive, as in the cases of chemical reaction. As 

 in Schmankewitsch's investigation, the conclusions are other- 

 wise open to the objection that they have entirely disregarded 

 the consideration of fundamental elements, and that the physi- 

 cal causes they cite have only set in motion a chain of internal 

 reactions, which are the immediate causes of the observed 

 modifications. Under these conditions, also, strong doubts 

 arise as to the efficiency of the physical causes thus demon- 

 strated, since the mode of experimentation does not exclude 

 the possible existence of other causes that might set the chain 

 of internal reactions going in the same or similar directions. 



Dr. H. S. Jennings's masterly studies "On the Reactions to 

 Stimuli in Unicellular Organisms " is one of the very few inves- 

 tigations not affected by such criticisms. These clearly estab- 

 lish the fact that a multiplicity of causes may bring about 

 precisely similar reactions on the part of several of the ciliated 

 Protozoa, like Paramecium, and that it is the organization and 



