578 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Eyelike Spots of Fishes.* — Professor F. Leydig comes to very 

 different conclusions concerning these organs to those which were 

 arrived at by Dr^ Ussow.| 



After a careful investigation of the subject, he finds that the bodies 

 in question have no sensory function, points out how they differ from 

 the eye, and dilates upon their striking resemblance to the electric or 

 pseudo-electric organs of certain other fishes. Those of them which 

 may be truly spoken of as " eyelike " have no real morphological re- 

 semblance to an eye, while the others, which are " mother-of-pearl " 

 or " luminous organs," exclude all possibility of their being sensory 

 bodies. The presence of a " tapetum " suggests the probability of 

 their being organs by which the scanty light of great depths may be 

 reflected, but observations on this subject are still required. In con- 

 clusion, it is suggested that the luminous function may only be a 

 secondary duty of these structures. 



Forces of Living Matter. | — T. Bernstein elaborates a theory 

 upon this subject which starts with the assumption that in living 

 organisms, as in nature generally, force undergoes two changes of con- 

 dition: (1) the " an-energic," consisting in passing into the poten- 

 tial from the active condition, and (2) the kat-energic, reversing this 

 process. The latter is naturally the one which is most commonly 

 observed ; the storage of force by plants under the influence of sunlight 

 is an example of the former, which is, however, not known to occur in 

 animals. Living matter can hence be defined as " that which by 

 virtue of a change of siibstances in its interior produces anenergic 

 and katenergic processes." The vital force which produces these 

 processes, but which does not operate in dead material, is explained 

 by the writer as chemical, and as due to the changes which occur in 

 the molecular combinations of the chemical substances of which the 

 matter is composed. His explanation is, in fact, based on that 

 chemico-physical theory of life which has long ranked among advanced 

 biological speculations. 



The particular form of force evoked by contact with foreign 

 bodies is called " contact force," and includes the forces of cohesion, 

 friction, capillarity, electrical tension, catalytic action, operation 

 of ferments. Living matter consists of molecules endowed with 

 cohesion. The visible composition of protoplasm, which is seen 

 under the Microscope to contain granules, agrees with this theory of 

 its being composed of chemically differing molecules, a conclusion 

 supported by the fact that the more granular it is, the greater its 

 chemical activity. The molecules represented by the protoplasmic 

 granules react upon the liquid which surrounds them, and under the 

 influence of their " contact force," take up matter for growth and 

 thus become centres of activity, whose subsequent structure is the 

 more complicated according as more molecules of different structure 



* 'Die Augenahnlichen Orgaue der Fisclie' (8vo, Bonn, 1881) 100 pp. 

 (10 pis.). See also article iu Pop. Sci. Eev. by Prof. F. J. Bell, v. (1881) 

 pp. 221-34 (1 pi.). 



t See this Journal, ii. (1870) p. 810. 



X^ Preisverk.-Programm. Univ. Halle, 1880. 



